"Good!" ejaculated Foster heartily.

"But at that, while I had the messages to turn over to Chief Connor, I was still in the dark as to the location of the sender. You know it is impossible to determine the direction or distance of a transmitting station by its waves—a ship at sea cannot be found by wireless unless its bearings are given. I concluded that the transmitting station must be in the vicinity of the government buildings, and the next relay within five miles—a greater wave length could be picked up by Arlington.

"On Tuesday night I got on the roof of one of the tall government buildings near here, and examining each roof as I crossed it looking for wireless antennae, I finally reached this house. I suspected I was being watched by Baron von Fincke, but managed to confuse him as to the direction I was taking, and finally clambered down into this attic through the scuttle. I was certain he was not aware of my identity, and for the sake of my plans, could not risk discovery.

"I had never been in your attic before," went on Miller, addressing Kathleen directly. "I was not even positive this was your house. When trying to find my way about I chanced upon the elevator shaft; I thought I was walking into a closet. At that moment I heard a footstep on the stair." Julie started and bent eagerly forward. "Desiring to get away as quickly as possible, I pressed the button for the elevator...."

"But the elevator must have been right there," interrupted Kathleen. "You could not have opened the outer mahogany door otherwise."

"So I realized when I had collected my wits," responded Miller. "Opening both doors, I bolted into the elevator a few minutes before the footsteps reached the attic."

"Was Spencer in the elevator then?" questioned Foster.

"I don't know; the elevator was dark, and I only used my flashlight for a second to show me the proper button to push for the first floor. It may be that Spencer was in the elevator, but I did not see him."

"But I did," volunteered Julie, coming forward. "And I it was you heard creeping upstairs. I believed that Henry was a spy and feared that he would steal Mr. Whitney's invention. Oh, monsieur, I was so intent on guarding the studio I never gave a thought to the sub-cellar. Frequently I watched all night in a niche I had fashioned near the wine closet, but on Tuesday, alas! I slept. The soft closing of the elevator door awoke me, and a person whom, by her walk and height, I judged to be mademoiselle, moved away from the elevator and went downstairs. Inspired by curiosity I entered the elevator a moment later, and switched on the light. I was almost overcome by the sight of M. Spencer, and turned out the light to shut away the view. I rushed to my room; but I could not rest. I was in agony for you, mademoiselle; that very afternoon I had warned you against Monsieur Spencer, and I feared—Oh, forgive me! that you had killed him because he had injured your father. After a long interval I crept upstairs to the attic and there tried to puzzle out what would be best to do for mademoiselle. Fearing the police would make me tell what I had seen, I ran away."

"When did you discover Sinclair Spencer in the elevator, Kathleen?" asked Miss Kiametia.

"When I went to find Julie on Wednesday morning," began Kathleen. "I was very absent-minded that morning, and after pressing the button for the elevator never noticed whether it was long arriving at my floor or not—the length of time it takes to reach a floor is the only way we have of judging from where it comes," she explained. "I entered the elevator intent only on pushing the basement button, which I did with my right hand, pulling the folding grille-work steel door to with my left hand. My back was turned to where Sinclair Spencer lay." She shuddered at the recollection. "Just before the elevator reached the basement I turned around and saw him. At first I was too stunned to move; then impulsively turned on the electric light so that I might see better, and discovered the finger print on his shirt.

"I don't suppose I would have been so quick to recognize the finger mark had not Miss Kiametia called my attention to it the day before when reading Captain M—Trent's palm," she resumed, not looking at Miller. "Horrified, I took my handkerchief and strove to make the stain unrecognizable; then suddenly I lost control of myself, and gave vent to scream after scream, and pressed my finger to the button nearest my hand. I was taken to the third floor, but the stopping of the elevator did not bring me self-control, and I think I should have lost my mind if the elevator had not moved of itself; I realized someone had pushed a floor button, but when the elevator stopped again and Miss Kiametia opened the door, I had lost all reason ... I...." She stopped, overcome by the recollection.

"My poor darling!" Miss Kiametia kissed her tenderly.

"How did you get that scar on your finger, Trent?" inquired Foster.

"While on a hunting trio with my father in the interior of South America my cousin and I, then fifteen and sixteen respectively, played a trick on one of our Indian guides. With the assistance of other Indians he branded my finger, saying by the half-moon we would be identified one from the other."

"That explains." Kathleen drew a long breath. "I racked my brain to remember whether I had seen the scar on your finger in Germany, and concluded you had perhaps received the injury since—since our last meeting."

"Tell me, Kathleen," broke in Miss Kiametia, "how did it happen that Sinclair Spencer had a flower from your bouquet in his hand?"

"I don't know, except that I wore the flowers the night before, and one may have fallen on the floor of the elevator and he picked it up."

Julie, who had followed Kathleen's every word with the closest attention, stepped to Miller Trent's side. "Monsieur, can you explain this telegram?" handing it to him. "Heinrich dropped it here late this afternoon."

Miller read the two words, then drew out a pencil. "Divide the word 'Trenton' to 'Trent on' and it reads: 'Trent on, hurry.' Yesterday afternoon I met a man named Hartzmann; he had known Karl intimately, and before I left him I realized something had aroused his suspicions. In New York he communicated with Buenos Ayres, found my whereabouts was unknown to my family, and jumped to the conclusion that I was impersonating my cousin."

"How do you know that?" demanded Foster.

"The Secret Service operative shadowing Hartzmann notified me of it today," answered Miller. "Obviously Hartzmann neglected to give any key to his dispatch to Heinrich, and the latter must have been entirely in the dark as to the real meaning of the warning. Von Fincke, whom Hartzmann apparently relied on to enlighten Heinrich, is out of town."

"Was it the operative's message to you about Hartzman which brought you here tonight?" asked Foster.

"No; I came hoping for an opportunity to examine Mr. Whitney's studio, and used a key to the front door which I had had made without Heinrich's knowledge. I thought by examining the studio I could find out who really went there last night; Heinrich brought me a set of the finger prints, and their startling resemblance to mine convinced me that a plot, devilish in its ingenuity, was being concocted and an attempt made to involve me in their machinations. On my way to the studio I saw Heinrich creeping downstairs and followed him. I never for one moment suspected Mrs. Whitney."

"Nor did anyone else," agreed Foster. "Except that Heinrich was shocked into confession by his having unintentionally killed Mrs. Whitney, thinking her Julie, we might never have learned the whole truth. Mitchell, after seeing Vincent's note to the Secretary of State, was thoroughly convinced you were guilty. By the way, Kiametia, what kept you so long upstairs when Mitchell asked you to find out if Miller was with Miss Kathleen?"

"Searching for that hypodermic needle; I believed Kathleen had taken it back."

"Did you see Mrs. Whitney upstairs?"

"No, I stopped for a moment in Winslow's room, and the nurse told me Minna had gone to her bedroom to lie down."

"What possessed her to go to the sub-cellar?" asked Foster.

"Probably a demon of unrest, or she may have had some message to leave for Heinrich," suggested Miller. "When he grappled with her in the dark she undoubtedly thought him a detective and dared not call out for fear of disclosing her identity. Probably she thought Heinrich out of the house, and never dreamed of his attacking her."

"And Heinrich mistook her for me." Julie's eyes glowed. "The hand of God! But, monsieur, why did you advise that I stay away from mademoiselle, and take me to that dreadful house?"

"Because, Julie, you were hysterical, and I feared if interviewed, you might make some statement in all good faith which would do Miss Kathleen irreparable injury. I also believed that your absence would serve to divert suspicion until I had a chance to find the real criminal; I met you before the inquest, and did not realize that your disappearance could be used to militate against Miss Kathleen. As for Mrs. Robinson"—he laughed slightly—"she keeps a private sanitarium, but just now has no patients. You were perfectly safe there, and I had Connor detail an operative to see that Heinrich did not torment you."

"What will become of Baron von Fincke?"

"Chief Connor and the State Department will handle his case. Connor told me he found the Baron's next door neighbor—a man named Frank Lutz...."

"Mercy, his wife's a member of the Sisters in Unity!" ejaculated Miss Kiametia.

"Lutz has a complete wireless transmitting station," went on Miller. "He was stunned by his arrest, and attempted suicide; Connor believes he can induce him to tell the locations of the other relay stations. Lutz had the wireless antennae strung along the ceilings in the upper corridors of his house. He declares they have just perfected a method to overcome static interference."

"And what about Heinrich?" asked Julie anxiously. "Will he escape?"

"No, he will undoubtedly pay the penalty of his crime; Mitchell took him in charge. Coroner Penfield was here a short time ago," added Miller, turning to Miss Kiametia. "He assisted us to take Mrs. Whitney to her bedroom; I left Rosa, the cook, there."

"Thank you," murmured Kathleen.

"I think I had better go upstairs and see to everything," and the spinster rose.

"Just a minute," Miller hesitated. "I felt that another and more determined attempt would be made to get Mr. Whitney's invention, Kathleen, and so suggested to him that he trust me with the drawings and specifications."

"Did he?"

"Yes, and I took them over and deposited them In the care of Chief Connor."

"A capital idea," exclaimed Foster.

"Then father's inventions are quite safe?" asked Kathleen.

"Yes. One is a camera for taking a map of the country from an airship; the other, still more marvelous—glass armor."

"Glass what!" chorused his listeners.

"Armor. A suit woven from a combination of mica and glass which Mauser bullets cannot penetrate."

"Good Lord!" Foster tugged at his hair until it stood upright.

"We can discuss the inventions at another time," announced the spinster, recovering from her astonishment. "I'll be upstairs, Kathleen, if you want me."

"Wait, I'm coming," but Foster turned on the threshold of the door, his curiosity mastering him. "There's just one question, Miss Kathleen; if you knew Karl von Mueller in Germany and, as you thought, met him here using the name of Charles Miller, why did you not at once conclude he was a German spy?"

"Because a year ago a school friend in Germany wrote me that Karl had disappeared after a duel, and she believed he was living in America under an assumed name," replied Kathleen, rising hurriedly. "Under those circumstances I thought it natural that he should have anglicized his name. Won't you stop—?"

"No, thanks," hastily. "I must see Kiametia. Good-night," and he disappeared into the hall. Miss Kiametia was talking to a white-capped nurse, who continued on her way upstairs on Foster's approach.

"Winslow has regained consciousness," announced Miss Kiametia, "and is sleeping naturally at last."

"I am delighted to hear it." Foster's tired face lighted with pleasure. "Shall I tell Kathleen?"

"No, not just yet; good news will keep, and I think she is entitled to the happiness of being with the man she loves."

"Do you never crave for that happiness, Kiametia?" and there was a wistful tenderness in his voice which made the spinster blink suspiciously. Suddenly she slipped her hand in his.

"Suppose I say yes, for a change," she whispered, burying her head on his shoulder, and with a thankful heart Foster held her close as he whispered tender, soothing words in her ear.

Neither Kathleen nor Miller cared to break the silence which prevailed after Foster's departure. Julie had slipped away at the same time. The pause became embarrassing, and in desperation Miller broke it.

"Kathleen, can you ever forgive me?" standing tall and straight before her. "I acted what seems now a contemptible part—but I had to know whom you were protecting, whom you suspected of killing Spencer—I thought—forgive me—your father guilty. Until you said last night that you were shielding me, I had no idea of such a possibility; then I jumped to the conclusion that you had seen me in this house on Tuesday night, and imagined you were the person creeping up to the attic. Then, then—God help me!—came the idea that German gold had corrupted you, also. I put you to a severe test; but I wanted my doubts that you might be in German pay absolutely refuted. Even when I threatened, you stood firm." He drew in his breath sharply. "You will never know how I admired you and hated myself."

She answered with a question. "How did you know of my friendship with your cousin, Karl?"

"We have always been confidentially intimate. In a moment of remorse he wrote me about you, telling me of your elopement, and stating that he took you to a village removed from a railroad for the wedding, and there found the priest too ill in bed to perform the ceremony; he confessed that he got drunk, lost his head, and—and—suggested that you dispense with the marriage ceremony."

Kathleen crimsoned to the roots of her hair. "Did he tell you that I indignantly refused, escaped from him, and started out to walk to the nearest railroad station. There I met John Hargraves, told him of my elopement, then accompanied him to the hotel in the next town where his cousin was stopping and spent the night with her, returning next day under her escort to the school. She explained to the principal that I had been visiting her, and smoothed over what promised to be a scandal."

"Yes, Karl wrote me of that also, but he did you the tardy justice of never mentioning your full name. When I met you at Chevy Chase I realized suddenly that you had mistaken me for him and—" Miller hesitated for a brief second—"I followed the game. Kathleen," his hitherto clear voice faltered, "I followed it to my own undoing. Each time that you repulsed me, you inspired me—first, with admiration; then, all unbidden, came love—love, so faithful and unswerving that not even the toils of treachery and false witness which threatened to envelope you, could alter it." He hesitated again, his face white and strained. "Tell me frankly, Kathleen, did you accept me on Tuesday only because you thought me Karl?"

"No." Kathleen's face was rosy with color and her eyes shone with a new radiance. Eagerly Miller clasped her hands and, bending his head, kissed them. "Whatever schoolgirl affection I cherished for Karl was long since dead before I met you. To you alone I gave my heart."

"My love, my love," he murmured softly. "May God aid me to atone to you for the sorrow of the past!" and looking up into his eyes, as his arms stole round her, Kathleen read there that the glory of life was hers at last.

THE END