"Senora de Moche!" exclaimed Craig, drawing me toward a palm.

It was indeed she. She had left the tea room and gone to her own room. Now she was alighting from the elevator, and had started toward the main dining-room, when her eyes had rested on Whitney. In spite of all that he had said to us about her, he had received the glance as a signal and was fluttering over to her like a moth to a flame.

What was the reason back of it all, I asked, as I thought of those wonderful eyes of hers? Was it a sort of auto-hypnotism? There was, I knew, a form of illusion known as ophthalmophobia—fear of the eye. It ranged from mere aversion at being gazed at all the way to the subjective development of real physical action from an otherwise trivial objective cause. Perhaps Inez was right about the eyes. One might fear them, and that fear might cause the precise thing to happen which the owner of the eyes intended. Still, as I reflected before, there was a much more important problem regarding eyes before us, that of the drug that was evidently being used in the cigarettes. What was it?

There was no chance of our gleaning anything now from these two who made such a strange pair. Kennedy turned and went out of the nearest entrance of the hotel.

"Central Park, West," he directed a cab driver, as we climbed in his machine; then to me, after giving the number, "I must see Inez Mendoza again before I can go ahead."

Inez was not expecting us so soon after leaving her at the hotel, yet I think was just a little glad that we had come.

"Did anything happen after I left?" she asked eagerly.

"We went back and saw Mr. Whitney," returned Craig. "I believe you are right. He is acting queerly,"

"Alfonso called me up," she volunteered.

"Was it about anything I should know?" queried Craig.

"Well," she hesitated, "he said he hoped that nothing that had taken place would change our own relations. That was about all. He was the dutiful son, and made no attempt to explain anything that was said."

Kennedy smiled. "You have not seen Mr. Lock, wood since, I suppose?" he asked.

"You always make me tell what I hadn't intended," she confessed, smiling back. "Yes, I couldn't help it. At least, I didn't see him. I called him up. I wanted to tell him what she had said and that it hadn't made any difference to me."

"What did he say?"

"I can't remember just how he put it, but I think he meant that it was something very much like that anonymous letter I received. We both feel that there is some one who wants to make trouble between us, and we are not going to let it happen."

If she had known of Kennedy's discovery of the shoe-prints, I feel sure that, as far as we were concerned, the case would have ended there. She was in no mood to be convinced by such a thing, would probably have insisted that some one was wearing a second-hand pair of his shoes.

Kennedy's eye had been travelling around the room as though searching for something.

"May I have a cigarette out of that case over there?" he asked, indicating a box of them on a table.

"Why—that is Mr. Lockwood's," she replied. "He left it here the last time he was here and I forgot to send it to him. Wait a minute. Let me get you some of father's."

She left the room. The moment the door closed Kennedy reached over and took one from the case. "I have some of Lockwood's already, but another won't matter, as long as I can get it," he said. "I thought it was her father's. When she brings them, smoke one with me, and be careful to save the stub. I want it."

A moment later she entered with a metal box that must have held several hundred. Kennedy and I each took one and lighted it, then for several minutes chatted as an excuse for staying. As for myself, I was glad enough to leave a pretty large stub, for I did not like it. These cigarettes, like those Whitney had offered us, had a peculiar flavour which I had not acquired a liking for.

"You must let me know whether anything else develops from the meeting in the tea room," said Kennedy finally, rising. "I shall be at the laboratory some time, I think."



XIV

THE INTERFEROMETER

Norton was waiting for us at the laboratory when we returned, evidently having been there some time.

"I was on my way to my apartment," he began, "when I thought I'd drop in to see how things are progressing."

"Slowly," returned Kennedy, throwing off his street clothes and getting into his laboratory togs.

"Have you seen Whitney since I had the break with him?" asked Norton, a trifle anxiously.

I wondered whether Kennedy would tell Norton what to expect from Whitney. He did not, however.

"Yes," he replied, "just now we had an appointment with Senora de Moche and some others and ran into him at the hotel for a few moments."

"What did he say about me?" queried Norton.

"He hadn't changed his mind," evaded Kennedy. "Have you heard anything from him?"

"Not a syllable. The break is final. Only I was wondering what he was telling people about me. He'll tell them something—his side of the case."

"Well," considered Kennedy, as though racking his brain for some remark which he remembered, while Norton watched him eagerly, "I do recall that he was terribly sore about the loss of the dagger, and seemed to think that it was your fault."

"I thought so, I knew it," replied Norton bitterly. "I can see it coming. All the trustees will hear of my gross negligence in letting the Museum be robbed. I suppose I ought to sit up there all night. Oh, by the way, there's another thing I wanted to ask you. Have you ever done anything with those shoe-prints you found in the dust of the mummy case?"

I glanced at Kennedy, wondering whether he felt that the time had come to reveal what he had discovered. He said nothing for a moment, but reached into a drawer and pulled out the papers, which I recognized.

"Here they are," he said, picking out the original impression which he had taken.

"Yes," repeated Norton, "but have you been able to do anything toward identifying them?"

"I found it rather hard to collect prints of the shoes of all of those I wished to compare. But I have them at last."

"And?" demanded Norton, leaning forward tensely.

"I find that there is one person whose shoe-prints are precisely the same as those we found in the Museum," went on Kennedy, tossing over the impression he had taken.

Norton scanned the two carefully. "I'm not a criminologist," he said excitedly, "but to my untrained eye it does seem as though you had here a replica of the first prints, all right." He laid them down and looked squarely at Kennedy. "Do you mind telling me whose feet made these prints?"

"Turn the second over. You will see the name written on it."

"Lockwood!" exclaimed Norton in a gasp as he read the name. "No— you don't mean it."

"I mean nothing less," repeated Kennedy firmly. "I do not say what happened afterwards, but Lockwood was in the Museum, hiding in the mummy case, that night."

Norton's mind was evidently working rapidly. "I wish I had your power of deduction, Kennedy," he said, at length. "I suppose you realize what this means?"

"What does it mean to you?" asked Kennedy, changing front.

Norton hesitated. "Well," he replied, "it means to me, I suppose, what it means to any one who stops to think. If Lockwood was there, he got the dagger. If he had the dagger—it was he who used it!"

The inference was so strong that Craig could not deny it. Whether it was his opinion or not was another matter.

"It fits in with other facts, too," continued Norton. "For instance, it was Lockwood who discovered the body of Mendoza."

"But the elevator boy took Lockwood up himself," objected Craig, more for the sake of promoting the discussion than to combat Norton.

"Yes—when he 'discovered' the thing. But it must have been done long before. Who knows? He may have entered. The deed might have been done. He may have left. No one saw him come or go. What then more likely to cover himself up than to return when he knew that his entrance would be known, and find the thing himself?"

Norton's reasoning was clever and plausible. Yet Kennedy scarcely nodded his head, one way or the other.

"You were acquainted with Lockwood?" he asked finally. "I mean to say, of course, before this affair."

"Yes, I met him in Lima just as I was starting out on my expedition. He was preparing to come to New York."

"What did you think of him then?"

"Oh, he was all right, I suppose. He wasn't the sort who would care much for an archaeologist. He cared more for a prospector going off into the hills than he did for me. And I—I admit that I am impossible. Archaeology is my life."

Norton continued to study the prints. "I can hardly believe my eyes," he murmured; then he looked up suddenly. "Does Whitney know about this—or Lockwood?"

Kennedy shook his head negatively.

"Because," pursued Norton, "an added inference to that I spoke of would be that the reason why they are so sure that they will find the treasure is that they are not going on tradition, as they say, but on the fact itself."

"A fair conclusion," agreed Craig.

"I wish the break could have been postponed," continued Norton. "Then I might have been of some service in my relation to Whitney. It's too late for me to be able to help you in that direction now, however."

"There is something you can do, though," said Craig.

"I shall be delighted," hastened Norton. "What is it?"

"You know Senora de Moche and Alfonso?"

"Yes."

"I wish that you would cultivate their acquaintance. I feel that they are very suspicious of me. Perhaps they may not be so with you."

"Is there any special thing you want to find out?"

"Yes—only I have slight hopes of doing so. You know that she is on most intimate terms with Whitney."

"I'm afraid I can't do much for you, then. She'll fight shy of me. He'll tell her his story."

"That will make no difference. She has already warned me against him. He has warned against her. It's a most remarkable situation. He is trying to get her into some kind of deal, yet all the time he is afraid she is double-crossing him. And at the same time he obeys her—well, like Alfonso would Inez if she'd only let him."

Norton frowned. "I don't like the way they hover about Inez Mendoza," he remarked. "Perhaps the Senora is after Whitney, while her son is after Inez. Lockwood seems to be impervious to her. Yes, I'll undertake that commission for you, only I can't promise what success I'll have."

Kennedy restored the shoe-prints to the drawer.

"I think that's gratifying progress," went on Norton. "First we know who stole the dagger. We know that the dagger killed Mendoza. You have even determined what the poison on the blade was. It seems to me that it remains only to determine who struck the actual blow. I tell you, Kennedy, Whitney will regret the day that he ever threw me over on so trivial a pretext."

Norton was pacing up and down excitedly now.

"My only fear is," he went on, "what the shock of such a thing will be on that poor little girl. First her father, then Lockwood. Why—the blow will be terrible. You must be careful, Kennedy."

"Never fear about that," reassured Craig. "Not a word of this has been breathed to her yet. We are a long way from fixing the guilt of the murder; inference is one thing, fact another. We must have facts. And the facts I want, which you may be able to get, relate to the strange actions of the de Moches."

Norton scanned Kennedy's face for some hint of what was back of the remark. But there was nothing there.

"They will bear watching, all right," he said, as he rose to go. "Old Mendoza was never quite the same after he became so intimate with her. And I think I can see a change in Whitney."

"What do you attribute it to?" asked Kennedy, without admitting that it had attracted his attention, too.

"I haven't the slightest idea," confessed Norton.

"Inez is as afraid of her as any of the rest," remarked Kennedy thoughtfully. "She says it is the evil eye."

"Not an uncommon belief among Latin-Americans," commented Norton. "In fact, I suppose there are people among us who believe in the evil eye yet. Still, you can hardly blame that little girl for believing it is almost anything. Well, I won't keep you any longer. I shall let you know of anything I find out from the de Moches. I think you are getting on remarkably."

Norton left us, his face much brighter than it had been when we met him at the door.

Kennedy, alone at last in the laboratory, went over to a cabinet and took out a peculiar-looking apparatus, which seemed, as nearly as I can describe it, to consist of a sort of triangular prism, set with its edge vertically on a rigid platform attached to a massive stand of brass.

"Norton seems to have suddenly become quite solicitous of the welfare of Senorita Mendoza," I hazarded, as he worked over the adjustment of the thing.

Kennedy smiled. "Every one seems to be—even Whitney," he returned, twisting a set-screw until he had the alignment of the various parts as he wanted it.

The telephone bell rang.

"Do you want to answer it?" I asked Craig.

"No," he replied, not even looking up from his work. "Find out who it is. Unless it is something very important say I am out on an investigation and that you have heard from me; that I shall not be either at the laboratory or the apartment until tomorrow morning. I must get this done to-night."

I took down the receiver.

"Hello, is this Professor Kennedy?" I recognized a voice.

"No," I replied. "Is there any message I can take?"

"This is Mr. Lockwood," came back the information I had already guessed. "When do you expect him?"

"It's Lockwood," I whispered to Craig, my hand over the transmitter.

"See what he wants," returned Craig. "Tell him what I told you."

I repeated Kennedy's message.

"Well, that's too bad," replied Lockwood. "I've just seen Mr. Whitney, and he tells me that Kennedy and you are pretty friendly with Norton, Of course, I knew that. I saw you at the Mendozas' together the first time. I'd like to have a talk with him about that man. I suppose he has told you all his side of the story of his relations with Whitney."

I am, if anything, a good listener, and so I said nothing, not even that he had better tell it to Kennedy in the morning, for it was such a novelty to have any of these people talk voluntarily that I really didn't much care whether I believed what they said or not.

"I used to know him down in Lima, you know," went on Lockwood. "What I want to say has to do with that dagger he says was stolen. I want to tell what I know of how he got it. There was an Indian mixed up in it who committed suicide—well, you tell Kennedy I'll see him in the morning."

Lockwood rang off, and I repeated what he had told me, as Kennedy continued to adjust the apparatus.

"Say," I exclaimed, as I finished. "That was a harry's of a commission you gave Norton just now, watching the de Moches. Why, they'd eat him alive if they got a chance, and I don't know that all's like a Sunday school on his part. Lockwood doesn't seem to think so."

Kennedy smiled quietly. "That was why I asked him to do it," he returned. "I thought that he wouldn't let much escape him. They all seem so down on him, he'll have to watch out. It will keep him busy, too, and that means a chance for us to work."

He had finished setting up the machine, and now went over to another drawer, from which he took the envelope of stubs which we had taken down at Whitney's office first. Then from the pocket of his street coat he drew both the second envelope of ashes and stubs, the whole cigarette from Lockwood's case, and the stubs which both of us had saved from the cigarettes that had once belonged to Mendoza.

Carefully he separated and labelled them all, so that there would be no chance for them to get mixed up. Then he picked up one of the stubs and lighted it. The smoke curled up in wreaths between a powerful light and the peculiar instrument, while Craig peered through a lens, manipulating the thing with exhaustless patience and skill. I watched him curiously, but said nothing, for he was studying something carefully, and I did not want to interrupt his train of thought.

Finally he beckoned me over. "Can you make anything out of that?" he asked.

I looked through the eye-piece, also. On a sort of fine grating all I could see was a number of strange lines.

"If you want an opinion from me," I said, with a laugh, "you'll have to tell me first what I am looking at."

"That," he explained, as I continued to gaze, "is one of the latest forms of the spectroscope, known as the interferometer, with delicately ruled gratings in which power to resolve the straight, close lines in the spectrum is carried to the limit of possibility. A small watch is delicate. But it bears no comparison to the delicacy of these defraction spectroscopes.

"Every substance, you know, is, when radiating light, characterized by what at first appears to be almost haphazard sets of spectral bands without relation to one another. But they are related by mathematical laws, and the apparent haphazard character is only the result of our lack of knowledge of how to interpret the results."

He resumed his place at the eye-piece to check over his results.

"Walter," he said finally, looking up at me with a twinkle in his eye, "I wish that you'd go out and find me a cat."

"A cat?" I repeated.

"Yes, a cat—felis domesticus, if it sounds better that way—a plain, ordinary cat."

I jammed on my hat and, late as it was, sallied forth on this apparently ridiculous mission.

Several belated passers-by and a policeman watched me as though I were a house-breaker, and I felt like a fool, but at last, by perseverance and tact, I managed to capture a fairly good specimen of the species, and carried it in my arms to the laboratory with some profanity and many scratches.



XV

THE WEED OF MADNESS

In my absence Craig had set to work on a peculiar apparatus, as though he were distilling something from several of the cigarette stubs which he had been studying by means of the interferometer.

"Here's your confounded cat," I ejaculated, as I placed the unhappy feline in a basket and waited patiently until finally he seemed to be rewarded for his patient labours. It was well along toward morning when he obtained in a test-tube a few drops of a colourless, odourless liquid.

"My interferometer gave me a clue," he remarked, as he held the tube up with satisfaction. "Without the tell-tale line in the spectrum which I was able to discover by its use I might have been hunting yet for it. It is so rare that no one would ever have thought, offhand, I suppose, to look for it. But here it is, I'm sure, only I wanted to be able to test it."

"So you are not going to try it on yourself," I said sarcastically, referring to his last experiment with a poison. "This time you are going to make the cat the dog."

"The cat will be better to test it on than a human being," he replied, with a glance that made me wince, for, after his performance with the curare, I felt that once the scientific furore was on him I might be called upon to become an unwilling martyr to science.

It was with an air of relief, both for himself and my own peace and safety, that I saw him take the cat out of the basket and hold her in his arms, smoothing her fur gently, to quiet the feelings that I had severely ruffled.

Then with a dropper he sucked up a bit of the liquid from the test-tube. I watched him intently as he let a small drop fall into the eye of the cat.

The cat blinked a moment, and I bent over to observe it more closely.

"It won't hurt the cat," he explained, "and it may help us."

As I looked at the cat's eye it seemed to enlarge, even under the glare of a light, shining forth, as it were, like the proverbial cat's eye under a bed.

What did it mean?

Was there such a thing, I wondered hastily, as the drug of the evil eye?

"What have you found?" I queried.

"Something very much like the so-called 'weed of madness,' I think," he replied slowly.

"The weed of madness?" I repeated.

"Yes. It is similar to the Mexican toloache and the Hindu datura, which you must have heard about."

I had heard of these weird drugs, but they had always seemed to be so far away and to belong rather to the atmosphere of civilizations different from New York. Yet, I reflected, what was to prevent the appearance of anything in such a cosmopolitan city, especially in a case so unusual as that which had so far baffled even Kennedy's skill?

"You know the jimson weed—the Jamestown weed, as it is so often called?" he continued, explaining. "It grows almost everywhere in the world, but most thrivingly in the tropics. All the poisons that I have mentioned are related to it in some way, I believe."

"I've seen the thing in lots and fields," I replied, "but I never thought it was of much importance."

"Well," he resumed, "the jimson weed on the Pacific coast, in some parts of the Andes, has large white flowers which exhale a faint, repulsive odour. It is a harmless-looking plant, with its thick tangle of leaves, a coarse green growth, with trumpet-shaped flowers. But to one who knows its properties it is quite too dangerously convenient for safety."

"But what has that to do with the evil eye?" I asked.

"Nothing; but it has much to do with the cigarettes that Whitney is smoking," he went on positively. "Those cigarettes have been doped!"

"Doped?" I interrogated, in surprise. "With this weed of madness, as you call it?"

"No, it isn't toloache that was used," he corrected. "I think it must be some particularly virulent variety of the jimson weed that was used, though that same weed in Mexico is, I am sure, what there they call toloache. Perhaps its virulence in this case lies in the method of concentration in preparing it. For instance, the seeds of the stramonium, which is the same thing, contain a much higher percentage of poison than the leaves and flowers. Perhaps the seeds were used. I can't say. But, then, that isn't at all necessary. It is the fact of its use that concerns us most now."

He took a drop of the liquid which he had isolated and added a drop of nitric acid. Then he evaporated it by gentle heat and it left a residue slightly yellow.

Next he took from the shelf over his table a bottle marked "Alcoholic Solution—Potassium Hydrate." He opened it and let a drop fall on the place where the liquid had evaporated.

Instantly the residue became a beautiful purple, turning rapidly to violet, then to dark red, and, finally, it disappeared altogether.

"Stramonium, all right," he nodded, with satisfaction at the achievement of his night's labours. "That was known as Vitali's test. Yes, there was stramonium in those cigarettes—datura stramonium—perhaps a trace of hyoscyamine."

I tried to look wise, but all I could think of was that, whatever his science showed me now, my instinct had been enough to prompt me not to smoke those cigarettes, though, of course, only Kennedy's science could tell what it was that caused that instinctive aversion.

"They are all like atropine, mydriatic alkaloids," he proceeded, "so called from the effect they have on the eye. Why, one-one hundred thousandth of a grain will affect the eye of a cat. You saw how it acted on our subject. It is more active in that way than atropine. Better yet, you remember how Whitney's eyes looked, how Inez said her father stared, and how she feared for Lockwood?"

"I remember," I said, still not able to detach the evil-eye idea quite from my mind. "How about the Senora's eyes? What makes them so—well, effective?"

"Oh," Craig answered quickly, "her pupils were normal enough. Didn't you notice that? It was the difference in Whitney's and the others' that first suggested making some tests."

"What is the effect?" I asked, wondering whether it might have contributed to the cause of Mendoza's death.

"The concentrated poison which has been used in these cigarettes does not kill—at least not outright. It is worse than that. Slowly it accumulates in the system. It acts on the brain."

I was listening, spellbound, as he made his disclosure. No wonder, I thought, even a scientific criminal stood in awe of Craig.

"Of all the dangers to be met with in superstitious countries, these mydratic alkaloids are among the worst. They offer a chance for crimes of the most fiendish nature—worse than with the gun or the stiletto. They are worse because there is so little fear of detection. That crime is the production of insanity!"

Horrible though the idea, and repulsive, I could not doubt it in the face of Craig's investigations and what I had already seen with my own eyes. In fact, it was necessary for me only to recall the mild sensations I myself had experienced, in order to be convinced of the possible effect intended by the insidious poison contained in the many cigarettes which Whitney, for instance, had smoked.

"But don't you suppose they know it?" I wondered. "Can't they tell it?"

"I suppose they have gradually become accustomed to it," Craig ventured. "If you have ever smoked one particular brand of cigarette you must have noticed how the manufacturer can gradually substitute a cheaper grade of tobacco without any large number of his patrons knowing anything about it. I imagine it might have been done in some way like that."

"But you would think they'd feel the effect and attribute it to smoking."

"Perhaps they do feel the effect. But when it comes to tracing causes, some people are loath to admit that tobacco and liquor can be the root of the evil. No, some one is slipping these cigarettes in on them, perhaps substituting the doped brand for those that are ordered. If you will notice, both Whitney and Lockwood have cigarettes that are made especially for them. So had Mendoza. It is a circumstance which some one has turned to account, though how and by whom the substitution has been made I cannot say yet. I wish I had time to follow out this one line, to the exclusion of everything else. But I've got to keep my fingers on every rope at once, else the thing will pull away from me. It is enough for the present that we know what the poison is. I shall take up the tracing of the person who is administering it the moment I get a hint."

It was almost daylight before Craig and I left the laboratory after his discovery of the manner of the cigarette poisoning by stramonium. But that was the only way in which he was able to make progress—taking time for each separate point by main force.

I was thoroughly tired, though not so much so that my dreams were not haunted by a succession of baleful eyes peering at me from the darkness.

I slept late, but was awakened by a knocking on the door. As I rose to answer it I saw through the open door of Kennedy's room that he had been about early and must already be at the laboratory. How he did it I don't know. My own newspaper experience had made me considerable of a nighthawk. But I always paid for it by sleeping the next day. With Kennedy, when he was on a case, even five hours of sleep was more than he seemed able to stand.

"Hello, Jameson," greeted a voice, as I opened the door. "Is Kennedy in—oh, he hasn't come back yet?"

It was Lockwood, at first eager to see Craig, then naturally crestfallen because he saw that he was not there.

"Yes," I replied, rubbing my eyes. "He must be at the laboratory. If you'll wait a minute while I slip on my clothes, I'll walk over there with you."

While I completed my hasty toilet, Lockwood sat in our living room, gazing about with fascination at the collection of trophies of the chase of criminals.

"This is positively a terrifying array of material, Jameson," he declared, as at last I emerged. "Between what Kennedy has here and what he has stowed away in that laboratory of his, I wonder that any one dares be a crook."

I could not help eying him keenly. Could he have spoken so heartily if he had known what it was, damning to himself, that Kennedy had tucked away in the laboratory? If he knew, he must have been a splendid actor, one of those whom only the minute blood-pressure test of the sphygmograph could induce to give up a secret, and then only in spite of himself.

"It is wonderful," I agreed. "Are you ready?"

We left the apartment and walked along in the bracing morning air toward the campus and the Chemistry Building. Sure enough, as I had expected, Kennedy was in his laboratory.

As we entered he was verifying his experiments and checking over his results, carefully endeavouring to isolate any of the other closely related mydriatic alkaloids that might be contained in the noxious fumes of the poisoned tobacco.

Though Craig was already convinced of what was going on, I knew that he always considered it a matter of considerable medico-legal importance to be exact, for if the affair ever came to the stage of securing an indictment the charge could be sustained only by specific proof.

As we appeared in the door, however, he laid aside his work, and greeted us.

"I suppose Jameson has already told you that I called you up last night—and what I said?" began Lockwood.

Kennedy nodded. "It was something about Norton, wasn't it?"

Lockwood leaned over impressively and almost whispered: "Of course, you are in no position to know, but there are ugly rumours current down in Lima among the natives regarding that dagger."

Kennedy did not appear to be particularly impressed. "Is that so?" he said merely. "What are they?"

"Well," resumed Lockwood, "I wasn't in Lima at the time. I was up here. But they tell me that there was something crooked about the way that that dagger was got away from an Indian—a brother of Senora de Moche." "Yes," replied Kennedy, "I know something about it. He committed suicide. But what has that to do with Norton?"

Lockwood hesitated, then shrugged his shoulders. "I should think the inference was plain," he insinuated. Then, looking at Craig fixedly, as though to take his measure, he added, "We are not out of touch with what is going on down there, even if we are several thousand miles away."

I wondered whether he had any information more than we had already obtained by X-raying the letter to Whitney signed "Haggerty." If he had, it was not his purpose, evidently, yet to disclose it. I felt from his manner that he was not playing a trump-card, but was just feeling us out by this lead.

"There was some crooked business about that dagger down there as well as here," he pursued. "There are many interests connected with it. Don't you think that it would be worth while watching Norton?" he paused, then added: "We do—and we're going to do it."

"Thank you very much," returned Kennedy quietly. "Mr. Whitney has already told me he intended to do so."

Lockwood eyed us critically, as though not quite sure what to make of the cool manner in which Craig took it.

"I think if I were you," he said at length, "I'd keep a close watch on the de Moches, both of them, too."

"Exactly," agreed Craig, without showing undue interest.

Lockwood had risen. "Well," he snapped, "you may not think much of what I am telling you now. But just wait until OUR detectives begin to dig up facts." No sooner had he left than I turned to Craig. "What was that?" I asked. "A plant?"

"Perhaps," he returned, clearing up the materials which he had been using.

The telephone rang.

"Hello, Norton," I heard Craig answer. "What's that? You are shadowed by some one—you think it is by Whitney?"

I had been expecting something of the sort, and listened attentively, but it was impossible to gather the drift of the one- sided conversation.

As Kennedy hung up the receiver I remarked, "So it was not a bluff, after all."

"I think my plan is working," he remarked thoughtfully. "You heard what he said? He guesses right the first time, that it is Whitney. The last thing he said was, 'I'll get even! I'll take some action!' and then he rang off. I think we'll hear something soon."

Instead of going out, Kennedy pulled out the several unsigned letters we had collected, and began the laborious process of studying the printing, analyzing it, in the hope that he might discover some new clue.



XVI

THE EAR IN THE WALL

Perhaps an hour later our laboratory door was flung open suddenly, and both Kennedy and I leaped to our feet.

There was Inez Mendoza, alone, pale and agitated.

"Tell me, Professor Kennedy," she cried, her hands clasped before her in frantic appeal, "tell me—it isn't true—is it? He wasn't there—no—no—no!"

She would have fainted if Craig had not sprung forward and caught her in time to place her in our only easy-chair.

"Walter," he said, "quick—that bottle of aromatic spirits of ammonia over there—the second from the left."

I handed it to him, and threw open the window to allow the fresh air to blow in. As I did so one of the papers Kennedy had been studying blew off the table, and, as luck would have it, fell almost before her. She saw it, and in her hypersensitive condition recognized it instantly.

"Oh—that anonymous letter!" she cried. "Tell me—you do not think that—the friend of my father's that it warned me to beware of— was—"

She did not finish the sentence. She did not need to do so.

"Please, Senorita," pleaded and soothed Kennedy, "try to be calm. What has happened? Tell me. What is it?"

The ammonia and the fresh air seemed to have done their work, for she managed to brace herself, gripping the arms of the chair tightly and looking up searchingly into Craig's face.

"It's about Chester," she managed to gasp; then seemed unable to go on.

It was the first time I had ever heard her use Lockwood's first name, and I knew that something had stirred her emotions more deeply than at any time since the death of her father.

"Yes," prompted Kennedy. "Go on."

"I have heard that you found foot-prints, shoe-prints, in the dust in the Museum after the dagger was stolen," she said, speaking rapidly, suppressing her feelings heroically. "Since then you have been collecting prints of shoes—and I've heard that the shoe- prints that were found are those of—of Mr. Lockwood. Oh, Professor Kennedy, it cannot be—there must be some mistake."

For a moment Kennedy did not say anything. He was evidently seeking some way in which to lead up to the revelation of the truth without too much shock.

"You remember that time in the tea room when we were sitting with Senora de Moche?" he asked finally.

"Yes," she said shortly, as though the very recollection were disagreeable to her.

Kennedy, however, had a disagreeable task, and he felt that it must be performed in the kindest manner.

"You remember then that she said she had one thing more to say, that it was about Mr. Whitney and Mr. Lockwood."

She was about to interrupt, but he hurried on, giving her no chance to do so. "She asked you to think it over. Suppose they did not have the dagger, she said. Then were their chances of finding the treasure any better than any one else had? And if they did have it, she asked what that meant. It is a dilemma, my dear Senorita, which you must meet some time. Why not meet it now?"

Her face was set. "You will remember, also, Professor Kennedy," she said, with a great effort controlling her voice, "that I said that Mr. Lockwood was not there to defend himself and I would not have him attacked by innuendo. I meant it to the Senora—I mean it to you!"

She had also meant it to defy him; but as she proceeded her voice broke, and before she knew it her nature had triumphed, and she was alternately sobbing and pleading.

For a minute or two Kennedy let her give vent to her emotions.

"It cannot be. It cannot be," she sobbed over and over. "He could not have been there. He could not have done it."

It was a terrible thing to have to disillusion her, but it was something now that had to be done. Kennedy had not sought to do so. He had postponed it in the hope of finding some other way. But now the thing was forced upon him.

"Who told you?" he asked finally.

"I was trying to read, to keep my mind occupied, as you asked me, when Juanita told me that there was some one in the living room who wanted to see me—a man. I thought it was either you or Mr. Jameson. But it was—Professor Norton—"

Kennedy and I exchanged glances. That was the action in revenge to Lockwood and Whitney which he had contemplated over the telephone. It was so cruel and harsh that I could have hated him for it, the more so as I recollected that it was he himself who had cautioned us against doing the very thing which now he had done in the heat of passion.

"Oh," she wailed, "he was very kind and considerate about it. He said he felt that it was his duty to tell me, that he would be anything, like an older brother, to me; that he could not see me blinded any longer to what was going on, and everybody knew, but had not love enough for me to tell. It was such a shock. I could not even speak. I simply ran from the room without another word to him, and Juanita found me lying on the bed. Then—I decided—I would come to you."

She paused, and her great, deep eyes looked up pathetically. "And you," she added bitterly, "you are going to tell me that he was right, that it is true. You can't prove it. Show me what it is that you have. I defy you!"

Somehow, as she rested and relieved her feelings, a new strength seemed to come to her. It was what Kennedy had been waiting for, the reaction that would leave her able for him to go on and plan for the future.

He reached into a drawer of a cabinet and pulled out the various shoe-prints which he had already shown Norton, and which he had studied and restudied so carefully.

"That is the print of the shoe in the dust of the Egyptian sarcophagus of the Museum," he said quietly. "Some one got in during the daytime and hid there until the place was locked. That is the print of Alfonso de Moche's shoe, that of Mr. Whitney's, and that of Mr. Lockwood's."

He said it quickly, as though trying to gloss it over. But she would not have it that way. She felt stronger, and she was going to see just what there was there. She took the prints and studied them, though her hand trembled. Hers was a remarkable mind. It took only seconds to see what others would have seen only in minutes. But it was not the reasoning faculty that was aroused by what she saw. It sank deep into her heart.

She flung the papers down.

"I don't believe it!" she defied. "There is some mistake. No—it cannot be true!"

It was a noble exhibition of faith. I think I have never seen any instant more tense than that in Kennedy's laboratory. There stood the beautiful girl declaring her faith in her lover, rejecting even the implication that it might have been he who had taken the dagger, perhaps murdered her father to insure the possession of her father's share of the treasure as well as the possession of herself.

Kennedy did not try to combat it. Instead he treated her very intuitions with respect. In him there was room for both fact and feeling.

"Senorita," he said finally, in a voice that was deep and thrilling with feeling, "have I ever been other than a friend to you? Have I ever given you cause to suspect even one little motive of mine?"

She faced him, and they looked into each other's eyes an instant. But it was long enough for the man to understand the woman and she to understand him.

"No," she murmured, glancing down again.

"Then trust me just this once. Do as I ask you."

For an instant she struggled with herself. What would he ask?

"What is it?" she questioned, raising her eyes to him again.

"Have you seen Mr. Lockwood?"

"No."

"Then, I want you to see him. Surely you wish to have no secrets from him any more than you would wish him to have anything secret from you. See him. Ask him frankly about it all. It is the only fair thing to him—it is only fair to yourself."

Senorita Mendoza was no coward. "I—I will," she almost whispered.

"Splendid!" exclaimed Kennedy in admiration. "I knew that you would. You are not the woman who could do otherwise. May I see that you get home safely? Walter, call a taxicab."

Senorita Mendoza was calmer, though pale and still nervous, when I returned. Kennedy handed her into the car and then returned to the laboratory for two rather large packages, which he handed to me.

"You must come along with us, Walter," he said. "We shall need you."

Scarcely a word was spoken as we jolted over the city pavements and at last reached the apartment. Inez and Craig entered and I followed, carrying just one of the packages as Craig had indicated by dumb show, leaving the other in the car, which was to wait.

"I think you had better write him a note," suggested Craig, as we entered the living room. "I don't want you to see him until you feel better—and, by the way, see him here."

She nodded with a wan smile, as though thinking how unusual it was for a meeting of lovers to be an ordeal, then excused herself to write the note.

She had no sooner disappeared than Kennedy unwrapped the package which I had brought. From it he took a cedar box, oblong, with a sort of black disc fixed to an arm on the top. In the face of the box were two little square holes, with sides of cedar which converged inward into the box, making a pair of little quadrangular pyramidal holes which ended in a small black circle in the interior.

He looked about the room quickly. Beside a window that opened out over a house several stories below stood a sectional bookcase. Into this bookcase, back of the books, in the shadow, he shoved the little box, to which he had already attached a spool of twisted wires. Then he opened the window and dropped the spool out, letting it unwind of its own weight until it fell on the roof far below. He shut the window and rejoined me without a word.

A moment later she returned with the dainty note which she had written. "Shall I send it by a messenger?" she asked.

"Yes, please," answered Kennedy, rising. As he moved a step to the door he held out his hand to her. "Senorita Mendoza," he said simply, in a tone that meant more than words, "you are a wonderful woman."

She took his hand without a word, and a moment later we were whisked down in the elevator.

"I must get on that roof on some pretext," remarked Kennedy, as we reached the street and he got his bearings. "Let me see, that house which backs up to the apartment is around the corner. Have the man drive us around there."

We located the house and mounted the steps. On the wall beside the brownstone door was pasted a little slip of paper, "Furnished Rooms."

"Splendid!" exclaimed Kennedy, as he read it. "Dismiss the taxi and meet me inside with the other package."

By the time I had paid the man and come up the steps again Kennedy had made a dicker with the landlady for a double room on the third floor for both of us, and, by payment of a week's rent, we were to have immediate possession.

"Our baggage will follow to-day," he explained, as we mounted the stairs to the room.

I thought the landlady would never get through expatiating upon what a select place she ran, and thus leave us alone in our room, but at last even her flood of words was stilled by demands from a servant downstairs who must be instructed if the selectness of the establishment were to be maintained.

No sooner were we alone than Kennedy tiptoed into the hall and made sure that we were not watched. It was then the work of only a few seconds to mount a ladder to a scuttle, unhook it, and gain the roof.

There, dangling down from the dizzy height above, swayed the twisted wire. He seized it, unrolled it some more, and sent me downstairs to catch it, as he swung it over the edge of the roof to one of our own windows. Then he rejoined me.

The other package, which had been heavier, consisted of another of those mysterious boxes, as well as several dry cells. Quickly he attached the wires to the box, placing the dry cells in the circuit. Then he began adjusting the mechanism of the box. So far I had only a vague idea of just what he had in mind, but gradually it began to dawn on me.

It was perhaps half an hour, perhaps longer, after we had left the Senorita, before, sure that everything was all right with his line and the batteries which he had brought, Kennedy turned a little lever that moved in a semicircle, touching one after another of a series of buttons on the face of the cedar box, meanwhile holding a little black disc from the back of the box to his ear as he adjusted the thing.

Nothing seemed to happen, but I could tell by the look of intentness on his face that he was getting along all right and was not worrying.

Suddenly the look on his face changed to one of extreme satisfaction. He dropped the disc he was holding to his ear back into its compartment and turned to me.

All at once it seemed as if the room in which we were was peopled by spirits. There was the sound of voices, loud, clear, distinct. It was uncanny.

"He has just come in," remarked Craig.

"Who?" I asked.

"Lockwood—can't you recognize his voice? Listen."

I did listen intently, and the more my ears became adjusted, the more plainly I could distinguish two voices, that of a man and that of a woman. It was indeed Lockwood and the Senorita, far above us.

I would have uttered an exclamation of amazement, but I could not miss what they were saying.

"Then you—you believe what he says?" asked Lockwood earnestly.

"Professor Kennedy has the prints," replied Inez tremulously.

"You saw them?"

"Yes."

"And you believe what HE says, too?"

There was a silence.

"What is it?" I asked, tapping the box lightly.

"A vocaphone," replied Kennedy. "The little box that hears and talks."

"Can they hear us?" I asked, in an awestruck whisper.

"Not unless I want them to hear," he replied, indicating a switch. "You remember, of course, the various mechanical and electrical ears, such as the detectaphone, which we have used for eavesdropping in other cases?"

I nodded.

"Well, this is a new application which has been made of the detectaphone. When I was using that disc from the compartment there, I had really a detectaphone. But this is even better. You see how neat it all is? This is the detective service, and more. We can 'listen in' and we don't have to use ear-pieces, either, for this is a regular loud-speaking telephone—it talks right out in meeting. Those square holes with the converging sides act as a sort of megaphone to the receivers, those little circles back there inside magnifying the sound and throwing it out here in the room, so that we can hear just as well as if we were up there in the room where they are talking. Listen—I think they are talking again."

"I suppose you know that Whitney and I have placed detectives on the trail of Norton," we could hear Lockwood say.

"You have?" came back the answer in a voice which for the first time sounded cold.

Lockwood must have recognized it. He had made a mistake. It was no sufficient answer to anything that he had done to assert that some one else had also done something.

"Inez," he said, and we could almost hear his feet as he moved over the floor in her direction in a last desperate appeal, "can't you trust me, when I tell you that everything is all right, that they are trying to ruin me—with you?"

There was a silence, during which we could almost hear her quick breath come and go.

"Women—not even Peruvian women are like the women of the past, Chester," she said at length. "We are not playthings. Perhaps we have hearts—but we also have heads. We are not to be taken up and put down as you please. We may love—but we also think. Chester, I have been to see Professor Kennedy, and—"

She stopped. It hurt too much to repeat what she had seen.

"Inez," he implored.

There was evidently a great struggle of love and suspicion going on in her, her love of him, her memory of her father, the recollection of what she had heard and seen. No one could have been as we were without wishing to help her. Yet no one could help her. She must work out her own life herself.

"Yes," she said finally, the struggle ended. "What is it?"

"Do you want me to tell you the truth?"

"Yes," she murmured.

His voice was low and tense.

"I was there—yes—but the dagger was gone!"



XVII

THE VOICE FROM THE AIR

"Do you believe it?" I asked Kennedy, as the voices died away, leaving us with a feeling that some one had gone out of the very room in which we were.

He shrugged his shoulders and said nothing. But I cannot say that he seemed ill pleased at the result of the interview.

"We'll just keep this vocaphone in," he remarked. "It may come in handy some time. Now, I think we had better go back to the laboratory! Things have begun to move."

On the way back he stopped to telephone Norton to meet us and a few minutes after we arrived, the archaeologist entered.

Kennedy lost no time in coming directly to the point, and Norton could see, in fact seemed to expect and be prepared for what was coming.

"Well," exclaimed Kennedy, "you've done it, this time!"

"I know what you are going to ask," returned Norton. "You are going to ask me why I did it. And I'm going to tell you. After I left you, the other day, I thought about it a long time. The more I thought, the more of a shame it seemed to me that a girl like that should be made a victim of her feelings. It wasn't so much what they have done to me that made me do it. I would have acted the same if it had been de Moche instead of Lockwood who was playing on her heart. I was afraid, to tell the truth, that you wouldn't tell her until it was too late. And she's too good to throw herself away and allow her fortune to be wasted by a couple of speculators."

"Very well," said Craig. "For the sake of argument, let us admit all that. What did you expect to accomplish by it?"

"Why—put an end to it, of course."

"But do you think she was going to accept as truth what you told her? Would that be natural for one so high-strung?"

"Perhaps not—right away. But I supposed she would come to you—as I see she has, for you know about it. After that, it was only a question of time. It may have been a heroic remedy, but the disease was critical."

"Suppose," suggested Craig, "that, after all, he told her that he was there in the Museum, but that he did not get the dagger. And suppose that she believed it. What then?"

Norton looked up quickly. "Did he tell her that?"

"I am supposing that he did," repeated Craig, declining to place himself in a position which might lead to disclosing how he found out.

"Then I should say that he was a great deal cleverer than I gave him credit for being," returned Norton.

"Well, it's done now, and can't be undone. Have you found out anything about the de Moches?"

"Not very much, I must admit. Of course, you know I'm not on the best of terms with them, for some reason or other. But I've been around the Prince Edward Albert a good deal, and I don't think they've been able to do much that I haven't some kind of line on. Alfonso seems to be moping. His professors here tell me that he has been neglecting his work sadly for the past few days. The Senora and Whitney seem to be as friendly as ever. I should say that they were going the pace fast, and it shows on him."

I glanced significantly at Kennedy, but he betrayed nothing that might lead one to suppose he had discovered the cause. Evidently he was not ready yet to come out into the open and expected further developments on the poisoned cigarette clue.

The telephone rang and Craig took down the receiver.

"Yes, this is Kennedy," he answered. "Oh, hello, Lockwood. What's that? You've been trying to get me all day? I just came in. Why, yes, I can see you in about half an hour."

"I guess I'd better clear out," said Norton with a bitter laugh, as Kennedy hung up the receiver. "There have been enough crimes committed without adding another murder to the list."

"Keep on watching the de Moches," requested Kennedy as Norton made his way to the door.

"Yes," agreed Norton. "They will bear it—particularly Alfonso. They are hot-blooded. You never know what they are going to do, and they keep their own counsel. I might hope that Lockwood would forget; but a de Moche—never."

I cannot say that I envied him very much, for doubtless what he said was true, though his danger might be mitigated by the fact that the dagger was no longer in his Museum. Still, it would never have left Peru, I reflected, if it had not been for him, and there is, even in the best of us, a smouldering desire for revenge.

Lockwood was more than prompt. I had expected that he would burst into the laboratory prepared to clean things out. Instead he came in as though nothing at all had happened.

"There's no use mincing words, Kennedy," he began. "You know that I know what has happened. That scoundrel, Norton, has told Inez that you had shoe-prints of some one who was in the Museum the night of the robbery and that those shoe-prints correspond with mine. As a matter of fact, Kennedy, I was there. I was there to get the dagger. But before I could get it, some one else must have done so. It was gone."

I wanted to believe Lockwood. As for Craig he said nothing.

"Then, when I did have a chance to get away that night," he continued, "I went over to Mendoza's. The rest you know."

"You have told Inez that?" asked Kennedy in order to seem properly surprised.

"Yes—and I think she believes me. I can't say. Things are strained with her. It will take time. I'm not one of those who can take a girl by main force and make her do what she won't do. I wish I could smooth things over. Let me see the prints."

Kennedy handed them over to him. He looked at them, long and closely, then handed back the damning evidence against himself.

"I know it would be no use to destroy these," he remarked. "In the first place that would really incriminate me. And in the second I suppose you have copies."

Craig smiled blandly.

"But I can tell you," he exclaimed, bringing his fist down on the laboratory table with a bang, "that before I lose that girl, somebody will pay for it—and there won't be any mistakes made, either."

The scowl on his face and the menacing look in his eye showed that now, with his back up against the wall, he was not bluffing.

He seemed to get little satisfaction out of his visit to us, and in fact I think he made it more in a spirit of bravado than anything else.

Lockwood had scarcely gone before Kennedy pulled out the University schedule, and ran his finger down it.

"Alfonso ought to be at a lecture in the School of Mines," he said finally, folding up the paper. "I wish you'd go over and see if he is there, and, if he is, ask him to step into the laboratory."

The lecture was in progress all right, but when I peered into the room it was evident that de Moche was not there. Norton was right. The young man was neglecting his work. Evidently the repeated rebuffs of Inez had worked havoc with him.

Nor was he at the hotel, as we found out by calling up.

There was only one other place that I could think of where he would be likely to be and that was at the apartment of Inez. Apparently the same idea occurred to Kennedy, for he suggested going back to our observation point in the boarding-house and finding out.

All the rest of the day we listened through the vocaphone, but without finding out a thing of interest. Now and then we would try the detective instrument, the little black disc in the back, but with no better success. Then we determined to listen in relays, one listening, while the other went out for dinner.

It must have been just a bit after dark that we could hear Inez talking in a low tone with Juanita.

A buzzing noise indicated that there was some one at the hall door.

"If it's any one for me," we heard Inez say, "tell them that I will be out directly. I'm not fit to be seen now."

The door was opened and a voice which we could not place asked for the senorita. A moment later Juanita returned and asked the visitor to be seated a few moments.

It was not long before we were suddenly aware that there was another person in the room. We could hear whispers. The faithful little vocaphone even picked them up and shot them down to us.

"Is everything all right?" whispered one, a new voice which was somewhat familiar I thought, but disguised beyond recognition.

"Yes. She'll be out in a minute."

"Now, remember what I told you. If this thing works you get fifty dollars more. I'd better put this mask on—damn it!—the slit's torn. It'll do. I'll hide here as soon as we hear her. That's a pretty nice private ambulance you have down there. Did you tell the elevator boy that she had suddenly been taken ill? That's all fixed, then. I've got the stuff—amyl nitrite—she'll go off like a shot. But we'll have to work quick. It only keeps her under a few minutes. I can't wear this mask down and I'm afraid some one will recognize me. Oh, you brought a beard. Good. I'll give you the signal. There must be no noise. Yes, I saw the stretcher where you left it in the hall."

"All right, Doc," returned the first and unfamiliar voice.

It all happened so quickly that we were completely bowled over for the moment. Who was the man addressed as "Doc"? There was no time to find out, no time to do anything, apparently, so quickly had the plot been sprung.

I looked at Kennedy, aghast, not knowing what to do in this unexpected crisis.

A moment later we heard a voice, "I'm sorry to have had to keep you waiting, but what is it that I can do for you?"

"Good God!" exclaimed Kennedy. "It is Inez herself!"

It was altogether too late to get over there to warn her, perhaps even to rescue her. What could we do? If we could only shout for help. But what good would that do, around a corner and so far away?

The vocaphone itself!

Quickly Kennedy turned another switch, of a rheostat, which accentuated a whisper to almost a shout.

"Don't be alarmed, Senorita," he cried. "This is Kennedy talking. Look under the bookcase by the window. You will find a cedar box. It is a detective vocaphone through which I can hear you and which is talking out to you. I have heard something just there just now- -"

"Yes, yes. Go on!"

"You are threatened. Shout! Shout!"

Just then there came a sound of a scuffle and a muffled cry which was not much above a whisper, as though a strong hand was clapped over her mouth.

What could we do?

"Juanita—Juanita—help!—police!" shouted Craig himself through the vocaphone.

An instant later we could hear other screams as Juanita heard and spread the alarm, not a second too soon.

"Come on, Walter," shouted Kennedy dashing out of the room, now that he was assured the alarm had been given.

We hurried around the corner, and into the apartment. One of the elevators was up, and no one was running the other, but we opened the gates and Kennedy ran it up by himself.

In the Mendoza apartment all was a babel of voices, every one talking at once.

"Did you get them?" Craig asked, looking about.

"No, sir, replied the elevator boy. "One of them came in from the ambulance and told me Miss Mendoza was suddenly taken sick. He rode up with the stretcher. The other one must have walked up."

"Do you know him? Has he ever been here before?"

"I can't say, sir. I didn't see him. At least, sir, when I heard the screams I ran in from the elevator, which the other one told me to wait with—left the door open. Just as I ran in, they dodged out past me, jumped into the car and rode down. I guess they must have had the engine of the ambulance motor running, sir, if they got away without you seeing them."

We were too late to head them from speeding off. But, at least, we had saved the Senorita. She was terribly upset by the attack, much shaken, but really all right.

"Have you any idea who it could be?" asked Craig as the faithful Juanita cared for her.

"I don't know the man who was waiting and 'Nita never saw him, either," she replied. "The one who jumped out from behind the portieres had on a mask and a false beard. But I didn't recognize anything about him."

Sudden as the attack had been and serious as might have been the outcome, we could not but feel happy that it had been frustrated.

Yet it seemed that some one ought to be delegated to see that such a thing could not occur again.

"We must think up some means of protecting you," soothed Kennedy. "Let me see, Mr. Lockwood and Mr. Whitney seem to be the closest to you. If you don't mind I'll call them up. I wonder if you'd object if we had a little luncheon up here, to-morrow? I have a special reason for asking it. I want to insure your safety and we may as well meet on common ground."

"There isn't the slightest objection in the world," she replied, as Kennedy reached for the telephone.

We had some little difficulty in locating both Lockwood and Whitney, but finally after a time managed to find them and arrange for the conference on the Senorita's safety for the next day.

Outside Kennedy gave instructions to the officer on the beat to watch the apartment particularly, and there was no reason now to fear a repetition of the attempt, at least that night.



XVIII

THE ANTIDOTE

Early the following morning Kennedy left me alone in the laboratory and made a trip downtown, where he visited a South American tobacco dealer and placed a rush order for a couple of hundred cigarettes exactly similar in shape and quality to those which Mendoza had smoked and which the others seemed also to prefer, except, however, that the deadly drug was left out.

While he was gone, it occurred to me to take up again the hunt for Alfonso. Norton was not in his little office, nor could I find Alfonso anywhere about the campus. In fact he seemed to have almost dropped out of his University work for the time. Accordingly, I turned my steps toward the Prince Edward Albert Hotel, in the hope that he might be there.

Inquiries of the clerk at the desk told me that he had been there, but was out just at that moment. I did not see Whitney around, nor the Senora, so I sat down to wait, having nothing better to do until Kennedy's return.

I was about to give it up and go, when I heard a cab drive up to the door and, looking up, I saw Alfonso get out. He saw me about the same time and we bowed. I do not think he even tried to avoid me.

"I haven't seen you for some time," I remarked, searching his face, which seemed to me to be paler than it had been.

"No," he replied. "I haven't been feeling very well lately and I've been running up into the country now and then to a quiet hotel—a sort of rest cure, I suppose you would call it. How are you? How is Senorita Inez?"

"Very well," I replied, wondering whether he had said what he did in the hope of establishing a complete alibi for the events of the night before.

Briefly I told him what had happened, omitting reference to the vocaphone and our real part in it.

"That is terrible," he exclaimed. "Oh, if she would only allow me to take care of her—I would take her back to our own country, where she would be safe, far away from these people who seek to prey on all of us."

He paced up and down nervously, and I could see that my information had added nothing to his peace of mind, though, at the same time, he had betrayed nothing on his part.

"I was just passing through," I said finally, looking at my watch, "and happened to see you. I hope your mother is well?"

"As well as is to be expected, surrounded by people who watch every act," he replied, I thought with a rap at us for having Norton about and so active, though I could not be sure.

We separated, and I hastened back to the laboratory to report to Craig that Alfonso was rusticating for his health.

Kennedy, on his part, had had an experience, though it was no more conclusive than my own. After he had left the tobacco district, he had walked up Wall Street to the subway. In the crowd he had seen Senora de Moche, although she had not seen him. He had turned and followed her until she entered the building in which Whitney and his associates had their offices. Whether it indicated that she was still leading them a chase, or they her, was impossible to determine, but it at least showed that they were still on friendly terms with each other.

In the laboratory he could always find something to do on the case, either in perfecting his chemical tests of the various drugs we had discovered, or in trying to decipher some similarities in the rough printing of the four warnings and the anonymous letter with the known handwriting of those connected with the case, many specimens of which he bad been quietly collecting. That in itself was a tremendously minute job, entailing not only a vast amount of expert knowledge such as he had collected in his years of studying crime scientifically, but the most exact measurements and careful weighing and balancing of trifles, which to the unscientific conveyed no meanings at all. Still, he seemed to be forging ahead, though he never betrayed what direction the evidence seemed to be taking.

The package of cigarettes which he had ordered downtown was delivered about an hour after his return and seemed to be the signal for him to drop work, for the meeting with Lockwood and Whitney had been set early. He stowed the package in his pockets and then went over to a cabinet in which he kept a number of rather uncommon drugs. From it he took a little vial which he shoved into his waistcoat pocket.

"Are you ready, Walter?" he asked.

"Whenever you are," I said, laying aside my writing.

Together we made our way down to the Mendoza apartment which had been the scene of the near-tragedy the night before. Outside, he paused for several moments to make inquiries about any suspicious persons that might have been seen lurking about the neighbourhood. None of the attendants in the apartment remembered having seen any, and they were now very alert after the two events, the murder and the attempted abduction. Not a clue seemed to have been left by the villain who had been called "Doc."

"How do you feel after your thrilling experience?" greeted Craig pleasantly, as Juanita admitted us and Inez came forward.

"Oh, Mr. Kennedy," she answered, with a note of sadness in her tone. "It makes me feel so alone in the world. If it were not for 'Nita—and you, I don't know what I should do."

"Doesn't Mr. Lockwood count?" asked Kennedy observantly.

"Of course—everything," she answered hastily. "But he has to be away so much on business, and—"

She paused and sighed. I could not help wondering whether, after all, his explanation of the dagger episode had been enough to satisfy her. Had she really accepted it?

Neither Lockwood nor Whitney had arrived, and Kennedy improved the opportunity to have a quiet talk aside with her, at which, I imagine, he was arranging a programme of what was to happen at this meeting and her part in it to co-operate with him.

She had left the room for a moment and we were alone. It was evidently a part of his plan, for no sooner was she gone than he opened the package of cigarettes which he had ordered and took out from the box in which Mendoza had kept his cigarettes those that were there, substituting those he had brought.

We had not long to wait, now. Lockwood and Whitney came together. I was interested to see the greeting of Inez and her lover. Was it pure fancy, or did I detect a trace of coldness as though there had sprung up something between them? As far as Lockwood was concerned, I felt sure that he was eager to break down any barrier that kept them from being as they had been.

Whitney took her hand and held it, in a playful sort of way. "I wish I were a young buck," he smiled. "No one would dare look at you—much less try to carry you off. Yes, we must be more careful of our little beauty, or we shall lose her."

They turned to greet us. I felt, as we shook hands, that it was much the same sort of handshake that one sees in the prize ring— to be followed by the clang of a bell, then all going to it, in battle royal, with the devil after the hindmost.

There was scarcely a chance for a preliminary bout before luncheon was announced, and we entered the cozy little dining-room to seat ourselves at the daintiest of tables. One could feel the hostess radiating hospitality, even on such a cross-current set of guests as we were, and for the time, I almost felt that it had been Kennedy's purpose to promote a love-feast instead of an armed truce.

Nothing was said about the main cause of our being together for some time, and the small talk almost lifted for a time the incubus that had settled down on all our lives since the tragedy in the den at the other end of the suite. But the fact could not be blinked.

Tacitly every one seemed to wait on Kennedy to sound the gong. Finally he did so.

"Of course," he began, clearing his throat, "there is no use making believe about anything. I think we all understand each other better now than we have ever done before. As for me, I am in this case under a promise to stick to it and fight it to the end. I suppose the rest of you are, also. But that need not prevent us agreeing on one thing. We can work together to protect Senorita Mendoza, at least, from such danger as threatened her last night."

"It's a dastardly shame," Lockwood exclaimed angrily, "that a man who would attempt a thing like that should go unpunished." "Show me how to trace him and I'll guarantee the punishment," rejoined Craig drily.

"I am not a detective," replied Lockwood.

Kennedy forebore to reply in kind, though I knew there was a ready answer on his tongue for the lover.

Ever since they had arrived, the Senorita had seen that they were well supplied with cigarettes from the case in which she and they supposed were the genuine South American brand of her father. Kennedy and I smoked them, too, although neither of us liked them very much. The others were smoking furiously.

"However," resumed Kennedy, "I do not feel that I want to intrude myself in this matter without being perfectly frank and having the approval of Senorita Mendoza. She has known both of you longer and more intimately than she has known me, although she has seen fit to place certain of her affairs in my hands, for which I trust I shall render a good account of my stewardship. It seems to me, though, that if there is, as we now know there is, some one whom we do not know"—he paused—"who has sunk so low as to wish to carry her off, apparently where she shall be out of the influence of her friends, it is only right that precautions should be taken to prevent it."

"What is your suggestion?" demanded Whitney, rather contentiously.

"Would there be any objection," asked Kennedy, "if I should ask my old friend,—or any of you may do it,—Deputy Commissioner O'Connor to detail a plainclothesman to watch this house and neighbourhood, especially at night?"

We watched the faces of the others. But it was really of no use.

"I think that is an excellent plan," decided Inez herself. "I shall feel much safer and surely none of you can be jealous of the city detectives."

Kennedy smiled. She had cut the Gordian knot with a blow. Neither Lockwood nor Whitney could object. The purpose of the luncheon was accomplished.

In fact he did not wait for further consideration, but excused himself from the table for a moment to call up our old friend O'Connor and tell him how gravely his man was needed. It was a matter of only a few minutes when he returned from the other room.

"He will detail Burke for this special service as long as we want him," reported Craig, sitting down again.

Inez was delighted, naturally, for the affair had been a terrific shock to her. I could see how relieved she felt, for I was sitting directly next to her.

The maid had, meanwhile brought in the coffee and Inez had been waiting to pour until Kennedy returned. She did not do so, now, either, however. It seemed as if she were waiting for some kind of signal from Kennedy.

"What a splendid view of the park you get here," remarked Kennedy turning toward the long, low windows that opened on a balustraded balcony. "Just look at that stream of automobiles passing on the west drive."

Common politeness dictated that all should turn and look, although there was no novelty in the sight for any of us.

As I have said, I was sitting next to Inez. To me she was a far more attractive sight than any view of the park. I barely looked out of the window. Imagine my surprise, then, at seeing her take advantage of the diversion to draw from the folds of her dress a little vial and pour a bit of yellowish, syrupy liquid into the cup of coffee which she was preparing for Whitney.

I could not help looking at her quickly. She saw that I had seen her and raised her other hand with a finger to her lips and an explanatory glance at Kennedy who was keeping the others interested. Instantly, I recognized the little vial which Craig had shoved into his waistcoat pocket. That had been the purpose of his whispered conference with her when we arrived. I said nothing, but determined to observe more closely.

More coffee and more cigarettes followed, always from the same box which was now on the table. The luncheon developed almost a real conversation. For the time, under the spell of our hostess, we nearly forgot that we were in reality bitter enemies.

My real interest, as time passed, centred in Whitney and I could not help watching him closely. Was it a fact, or was it merely my imagination? He seemed quite different. The pupils of his eyes did not seem to be quite so dilated as they had been at other times, or even when he arrived. Even his heart action appeared to be more normal. I think Inez noticed it, too. There was none of the wildness in his conversation, such as there often had been at other times.

Our party was prolonged beyond the time we had expected, but, although he had much on his mind, Kennedy made no move to break it up. In fact he did everything to encourage it.

At last, however, the others did notice the time, and I think it was with sincere regret that the truce was broken. Even then, no parting shots were indulged in.

As we left, Inez thanked Kennedy for his consideration, and I am sure that that in itself was reward enough. We parted from Lockwood, who wished to remain a little while, and rode down in the elevator with Whitney, a changed man.

"I'll walk over to the elevated with you," he said. "I was going to my hotel, but I think I'll go down to the office instead."

Evidently he had got Senora de Moche out of his mind, at least temporarily, I thought. Then for the first time I recalled that during the whole luncheon there had been no reference to either the Senora or Alfonso, though both must have been in our minds often.

"What was it you had Inez drop into Whitney's coffee?" I asked Craig as we parted from him and rode uptown.

"You saw that?" he smiled. "It was pilocarpine, jaborandi, a plant found largely in Brazil, one of the antidotes for stramonium poisoning. It doesn't work with every one. But it seems to have done so with him. Besides, the caffeine in the coffee probably aided the pilocarpine. Then, too, I made them smoke cigarettes without the dope that is being fed them. Lockwood's case, for some reason, hasn't gone far. But did you notice how the treatment contracted the pupils of Whitney's eyes almost back to normal again?"

I had and said so, adding, "But what was your idea?"

"I think I've got at the case from a brand-new angle," he replied. "Unless I am greatly mistaken, when the person who is doing the doping sees that Whitney is getting better—why, I think you all noticed it, Inez and Lockwood as well as you—it will mean another attempt to substitute more cigarettes doped with that drug. I think it's by substitution that it's being done. We'll see."

At the laboratory, Kennedy called Norton and described briefly what had happened, especially to Whitney.

"Now is your chance, Norton," he added, "to do some real good work. I want some one to watch the Senora, see if she, too, notes the difference in him. Understand?"

"Perfectly," returned Norton. "That is something I think I can do."



XIX

THE BURGLAR POWDER

It was not until after dinner that we heard again from Norton. He had evidently spent the time faithfully hanging about the Prince Edward Albert, but Whitney had not come in, although the Senora and Alfonso were about.

"I saw them leaving the dining-room," he reported to us in the laboratory directly afterward, "just as Whitney came in. They could not see me. I took good care of that. But, say, there is a change in Whitney, isn't there? I wonder what caused it?"

"It's as noticeable as that?" asked Kennedy. "And did she notice it?"

"I'm sure of it," replied Norton confidently. "She couldn't help it. Besides, after he left her and went into the dining-room himself she and Alfonso seemed to be discussing something. I'm sure it was that."

Kennedy said nothing, except to thank Norton and compliment him on his powers of observation. Norton took the praise with evident satisfaction, and after a moment excused himself, saying that he had some work to do over in the Museum.

He had no sooner gone than Kennedy took from a drawer a little packet of powder and an atomizer full of liquid, which he dropped into his pocket.

"I think the Prince Edward Albert will be the scene of our operations, to-night, Walter," he announced, reaching for his hat.

He seemed to be in a hurry and it was not many minutes before we entered. As he passed the dining-room he glanced in. There was Whitney, not half through a leisurely dinner. Neither of the de Moches seemed to be downstairs.

Kennedy sauntered over to the desk and looked over the register. We already knew that Whitney and the Senora had suites on the eighth floor, on opposite sides and at opposite ends of the hall. The de Moche suite was under the number 810. That of Whitney was 825.

"Is either 823 or 827 vacant?" asked Kennedy as the clerk came over to us.

He turned to look over his list. "Yes, 827 is vacant," he found.

"I'd like to have it," said Kennedy, making some excuse about our luggage being delayed, as he paid for it for the night.

"Front!" called the clerk, and a moment later we found ourselves in the elevator riding up.

The halls were deserted at that time in the evening except for a belated theatre-goer, and in a few minutes there would ensue a period in which there was likely to be no one about.

We entered the room next to Whitney's without being observed by any one of whom we cared. The boy left us, and it was a simple matter after that to open a rather heavy door that communicated between the two suites and was not protected by a Yale lock.

Instead of switching on the lights, Kennedy first looked about carefully until he was assured that there was no one there. It seemed to me to be an unnecessary caution, for we knew Whitney was down-stairs and would probably be there a long time. But he seemed to think it necessary. Positive that we were alone, he made a hasty survey of the rooms. Then he seemed to select as a starting-point a table in one corner of the sitting-room on which lay a humidor and a heavy metal box for cigarettes.

Quickly he sprinkled on the floor, from the hall door to the table on which the case of cigarettes lay, some of the powder which I had seen him wrap up in the laboratory before we left. Then, with the atomizer, he sprayed over it something that had a pungent, familiar odour—walking backwards from the hall door to the table, as he sprayed.

"Don't you want more light?" I asked, starting to cross to a window to let the moonlight stream in.

"Don't walk on it, Walter," he whispered, pushing me back. "No, I don't need any more light."

"What are you doing?" I asked, mystified at his actions.

"First I sprinkled some powdered iodine on the floor," he replied, "and then sprayed over just enough ammonia to moisten it. It will evaporate quickly, leaving what I call my anti-burglar powder."

"I'm sure I wouldn't be thought one of the fraternity for the world," I observed, stepping aside to give him all the room he wanted in which to operate.

He had finished his work by this time and now the evening wind was blowing away the slight fumes that had arisen. For a few moments he left our door into Whitney's room open, in order to insure clearing away the odour. Then he quietly closed it, but did not lock it again.

We waited a few minutes, then Craig leaned over to me. "I wish you'd go down and see how near Whitney is through dinner," he said. "If he is through, do something, anything to keep him down there. Only be as careful as you can not to be seen by any one who knows us."

I rode down in an empty elevator and cautiously made my way to the dining-room. Whitney had finished much sooner than I had expected and was not there. Much as I wanted not to be seen, I found that it was necessary to make a tour of the hotel to find him and I did so, wondering what expedient I would adopt to keep him down there if I found him. I did not have to adopt any, however. Whitney was almost alone in the writing-room, and a big pile of letters beside him showed me that he would be busy for some time. I rode back to the room to tell Craig, flattering myself that I had not been seen.

"Good," he exclaimed. "I don't think we'll have to wait much longer, if anything at all is going to happen."

In the darkness we settled ourselves for another vigil that was to last we knew not how long. Neither of us spoke as we half crouched in the shadow of our room, listening.

Slowly the time passed. Would any one take advantage of the opportunity to tamper with the box of cigarettes on the table?

I fell to speculating. Who could it possibly have been that had conceived this devilish plot? What was back of it all? I wondered whether it were possible that Lockwood, now that Mendoza was out of the way, could desire to remove Whitney, the sole remaining impediment to possessing the whole of the treasure as well as Inez? Then there were the Senora and Alfonso, the one with a deep race and family grievance, the other a rejected suitor. What might not they do with some weird South American poison?

Once or twice we heard the elevator door clang and waited expectantly, but nothing happened. I began to wonder whether, even if some one had a pass-key to the suite, we could hear him enter if he was quiet. The outside hall was thickly carpeted, and deadened every footfall if one exercised only reasonable care. The rooms themselves were much the same.

"Don't you think we might have the door ajar a little?" I suggested anxiously.

"Sh!" was Kennedy's only comment in the negative.

I glanced now and then at my watch and by straining my eyes was surprised to see how early it was yet. The minutes were surely leaden-footed.

In the darkness, I fell again to reviewing the weird succession of events. I am not by nature superstitious, but in the black silence I could well imagine a staring succession of eyes, beginning with the dilated pupils of Whitney and passing on to the corpse-like expression of Mendoza, but always ending with the remarkable, piercing, black eyes of the Indian woman with the melancholy- visaged son, as they had impressed me the first time I saw them and, in fact, ever since. Was it a freak of my mind, or was there some reason for it?

Suddenly I heard in the next room what sounded like a series of little explosions, as though some one were treading on match heads.

"My burglar powder works," muttered Craig to me in a hoarse whisper. "Every step, even those of a mouse running across, sets it off!"

He rose quickly and threw open the door into Whitney's suite. I sprang after him.

There, in the shadows, I saw a dark form, starting back in quick retreat. But we were too late. He was cat-like, too quick for us.

In the dim light of the little explosions we could catch a glimpse of the person who had been craftily working with the dread drug to drive Whitney and others insane. But the face was masked!

He banged shut the door after him and fled down the hall, making a turn to a flight of steps.

We followed, and at the steps paused a moment. "You go up, Walter," shouted Kennedy. "I'll go down."

It was fifteen minutes later before we met downstairs, neither of us with a trace of the intruder. He seemed to have vanished like smoke.

"Must have had a room, like ourselves," remarked Craig somewhat chagrined at the outcome of his scheme. "And if he was clever enough to have a room, he is clever enough to have a disguise that would fool the elevator boys for a minute. No, he has gone. But I'll wager he won't try any more substitutions of stramonium- poisoned cigarettes for a while. It was too close to be comfortable."

We were baffled again, and this time by a mysterious masked man. Could it be the same whom we heard over the vocaphone addressed as "Doc"? Perhaps it was, but that gave us no hint as to his identity. He seemed just as far away as ever.

We waited around the elevators for some time, but nothing happened. Kennedy even sought out the manager of the hotel, and after telling who he was, had a search made of the guests who might be suspected. The best we could do was to leave word that the employees might be put on the lookout for anything of a suspicious nature.

Whitney, the innocent cause of all this commotion, was still in the writing-room with his letters.

"I think I ought to tell him," decided Kennedy as we passed down the lobby.

He seemed surprised to see us, as we strolled up to his writing desk, but pushed aside the few letters which he had not finished and asked us to sit down.

"I don't know whether you have noticed it," began Craig, "but I wonder how you feel?"

Whitney had expected something else rather than his health as the subject of a quiz. "Pretty good now," he answered before he knew it, "although I must admit that for the past few days I have wondered whether I wasn't slowing up a bit—or rather going too fast."

"Would you like to know why you feel that way?" asked Craig.

Whitney was now genuinely puzzled. It was perfectly evident, as it had been all the time, that he had not the slightest inkling of what was going on.

As Craig briefly unfolded what we had discovered and the reason for it, Whitney watched him aghast.

"Poisoned cigarettes," he repeated slowly. "Well, who would ever have thought it. You can bet your last jitney I'll be careful what I smoke in the future, if I have to smoke only original packages. And it was that, partly, that ailed Mendoza?"

Kennedy nodded. "Don't take any pilocarpine, just because I told you that was what I used. You have given yourself the best prescription, just now. Be careful what you smoke. And, don't get excited if you seem to be stepping on matches up there in your room for a little while, either. It's nothing."

Whitney's only known way of thanking anybody was to invite them to adjourn to the cafe, and accordingly we started across the hall, after he had gathered up his correspondence. The information had made more work that night impossible for him.

As we crossed from the writing-room, we saw Alfonso de Moche coming in from the street. He saw us and came over to speak. Was it a coincidence, or was it merely a blind? Was he the one who had got away and now calculated to come back and throw us off guard?

Whitney asked him where he had been, but he replied quickly that his mother had not been feeling very well after dinner and had gone to bed, while he strolled out and had dropped into a picture show. That, I felt, was at least clever. The intruder had been a man.

De Moche excused himself, and we continued our walk to the cafe, where Whitney restored his shattered peace of mind somewhat.

"What's the result of your detective work on Norton?" ventured Kennedy at last, seeing that Whitney was in a more expansive frame of mind, and taking a chance.

"Oh," returned Whitney, "he's scared, all right. Why, he has been hanging around this hotel—watching me. He thinks I don't know it, I suppose, but I do."

Kennedy and I exchanged glances.

"But he's slippery," went on Whitney. "He knows that he is being shadowed and the men tell me that they lose him, now and then. To tell the truth I don't trust most of these private detectives. I think their little tissue paper reports are half-faked, anyhow."

He seemed to want to say no more on the subject, from which I took it that he had discovered nothing of importance.

"One thing, though," he recollected, after a moment. "He has been going to see Inez Mendoza, they tell me."

"Yes?" queried Kennedy.

"Confound him. He pretty nearly got Lockwood in bad with her, too," said Whitney, then leaning over confidentially added, "Say, Kennedy, honestly, now, you don't believe that shoe-print stuff, do you?"

"I see no reason to doubt it," returned Kennedy with diplomatic firmness. "Why?"

"Well," continued Whitney, still confidential, "we haven't got the dagger—that's all. There—I never actually asserted that before, though I've given every one to understand that our plans are based on something more than hot-air. We haven't got it, and we never had it."

"Then who has it?" asked Kennedy colourlessly.

Whitney shook his head. "I don't know," he said merely.

"And these attacks on you—this cigarette business—how do you explain that," asked Craig, "if you haven't the dagger?"