At the thought Dick had turned, to discover that Jack was not beside him. It was very dark, but in a moment he caught the tiniest movement over by the hedge, and saw a spot a little darker than the rest of the ground about it. Jack, he saw at once, had taken the one faint chance there was, dropped down, and crawled away, trusting that their captors had not counted their party, and might not miss one boy.

Just in time he slipped through a hole in the hedge. The next moment one of the headlights of the grey motor flashed out, almost blinding the three of them, as they held up their hands. In its light four men, well armed with revolvers, were revealed.

"Donnerwetter!" said one. "I made sure there were four of them! So! Vell, it is enough. Into the car with them!"

No pretence about this chap! He was German, and didn't care who knew it. He was unlike the man who had disguised himself as an English officer, at the house of the heliograph, but had betrayed himself and set this whole train of adventure going by his single slip and fall from idiomatic English that Harry Fleming's sharp ears had caught.

Dick was thrilled, somehow, even while he was being roughly bundled toward the motor. If these fellows were as bold as this, cutting telephone wires, running about without lights, giving up all secrecy and pretence, it must mean that the occasion for which they had come was nearly over. It must mean that their task, whatever it might be, was nearly accomplished—the blow they had come to strike was about ready to be driven home.

"'Ere, who are you a shovin' off?" complained one of the linemen, as he was pushed toward the motor. He made some effort to resist but the next moment he pitched forward. One of the Germans had struck him on the head with the butt of his revolver. It was a stunning blow, and the man was certainly silenced. Dick recoiled angrily from the sight, but he kept quiet. He knew he could do no good by interfering. But the sheer, unnecessary brutality of it shocked and angered him. He felt that Englishmen, or Americans, would not treat a prisoner so—especially one who had not been fighting. These men were not even soldiers; they were spies, which made the act the more outrageous.

They were serving their country, however, for all that, and that softened Dick's feeling toward them a little. True, they were performing their service in a sneaky, underhanded way that went against his grain. But it was service, and he knew that England, too, probably used spies, forced to do so for self-defence. He realized the value of the spy's work, and the courage that work required. If these men were captured they would not share the fate of those surrendering in battle but would be shot, or hung, without ceremony.

A minute later he was forced into the tonneau of the car, where he lay curled up on the floor. Two of the Germans sat in the cushioned seat while the two linemen, the one who had been hit still unconscious, were pitched in beside him. The other two Germans were in front, and the car began to move at a snail's pace. The man beside the driver began speaking in German; his companion replied. But one of the two behind interrupted, sharply.

"Speak English, dummer kerl!" he exclaimed, angrily. "These English people have not much sense, but if a passerby should hear us speaking German, he would be suspicious. Our words he cannot hear and if they are in English he will think all is well."

"This is one of those we heard of this afternoon," said the driver. "This Boy Scout. The other is riding to London—but he will not go so far."

He laughed at that, and Dick, knowing he was speaking of Harry, shuddered.

"Ja, that is all arranged," said the leader, with a chuckle. "Not for long—that could not be. But we need only a few hours more. By this time to-morrow morning all will be done. He comes, Von Wedel?"

"We got the word to-night—yes," said the other man. "All is arranged for him. Ealing—Houndsditch, first. There are the soldiers. Then Buckingham Palace. Ah, what a lesson we shall teach these English! Then the buildings at Whitehall. We shall strike at the heart of their empire—the heart and the brains!"

Dick listened, appalled. Did they think, then, that he, a boy, could not understand? Or were they so sure of success that it did not matter? As a matter of fact, he did not fully understand. Who was Von Wedel? What was he going to do when he came? And how was he coming?

However, it was not the time for speculation. There was the chance that any moment they might say something he would understand, and, moreover, if he got away, it was possible that he might repeat what he heard to those who would be able to make more use of it.

Just then the leader's foot touched Dick, and he drew away. The German looked down at him, and laughed.

"Frightened?" he said. "We won't hurt you! What a country! It sends its children out against us!"

His manner was kindly enough, and Dick felt himself warming a little to the big man in spite of himself.

"Listen, boy," said the leader. "You have seen things that were not for your eyes. So you are to be put where knowledge of them will do no harm—for a few hours. Then you can go. But until we have finished our work, you must be kept. You shall not be hurt—I say it."

Dick did not answer. He was thinking hard. He wondered if Jack would try to rescue him. They were getting very near Bray Park, he felt, and he thought that, once inside, neither Jack nor anyone else could get him out until these men who had captured him were willing. Then the car stopped suddenly. Dick saw that they were outside a little house.

"Get out," said the leader.

Dick and the telephone man who had not been hurt obeyed; the other lineman was lifted out, more considerately this time.

"Inside!" said the German with the thick, guttural voice. He pointed to the open door, and they went inside. One of the Germans followed them, and stood in the open door.

"Werner, you are responsible for the prisoners, especially the boy," said the leader. "See that none of them escape. You will be relieved at the proper time. You understand?"

"Ja, Herr Ritter!" said the man. "Zu befehl!"

He saluted, and for the first time Dick had the feeling that this strange procedure was, in some sense, military, even though there were no uniforms. Then the door shut, and they were left in the house.

It was just outside of Bray Park—he remembered it now. A tiny box of a place it was, too, but solidly built of stone. It might have been used as a tool house. There was one window; that and the door were the only means of egress. The German looked hard at the window and laughed. Dick saw then that it was barred. To get out that way, even if he had the chance, would be impossible. And the guard evidently decided that. He lay down across the door.

"So!" he said. "I shall sleep—but with one ear open! You cannot get out except across me. And I am a light sleeper!"

Dick sat there, pondering wretchedly. The man who had been struck on the head was breathing stertorously. His companion soon dropped off to sleep, like the German, so that Dick was the only one awake. Through the window, presently, came the herald of the dawn, the slowly advancing light. And suddenly Dick saw a shadow against the light, looked up intently, and saw that it was Jack Young. Jack pointed. Dick, not quite understanding, moved to the spot at which he pointed.

"Stay there!" said Jack, soundlessly. His lips formed the words but he did not utter them. He nodded up and down vehemently, however, and Dick understood him, and that he was to stay where he was. He nodded in return, and settled down in his new position. And then Jack dropped out of sight.

For a long time, while the dawn waxed and the light through the window grew stronger, Dick sat there wondering. Only the breathing of the three men disturbed the quiet of the little hut. But then, from behind him, he grew conscious of a faint noise. Not quite a noise, either; it was more a vibration. He felt the earthen floor of the hut trembling beneath him. And then at last he understood.

He had nearly an hour still to wait. But at last the earth cracked and yawned where he had been sitting. He heard a faint whisper.

"Dig it out a little—there's a big hole underneath. You can squirm your way through. I'm going to back out now."

Dick obeyed, and a moment later he was working his way down, head first, through the tunnel Jack had dug from the outside. He was small and slight and he got through, somehow, though he was short of breath and dirtier than he had ever been in his life when at last he was able to straighten up—free.

"Come on!" cried Jack. "We've no time to lose. I've got a couple of bicycles here. We'd better run for it."

Run for it they did, but there was no alarm. Behind them was the hut, quiet and peaceful. And beyond the hut was the menace of Bray Park and the mysteries of which the Germans had spoken in the great grey motor car.



CHAPTER XV

A DARING RUSE

Harry, furious as he was when he saw Graves allowed to go off after the false accusation that had caused his arrest, was still able to control himself sufficiently to think. He was beginning to see the whole plot now, or to think he saw it. He remembered things that had seemed trivial at the time of their occurrence, but that loomed up importantly now. And one of the first things he realized was that he was probably in no great danger, that the charge against him had not been made with the serious idea of securing his conviction, but simply to cause his detention for a little while, and to discredit any information he might have.

He could no longer doubt that Graves was in league with the spies on whose trail he and Dick had fallen. And he understood that, if he kept quiet, all would soon be all right for him. But if he did that, the plans of the Germans would succeed. He had seen already an example of what they could do, in the destruction of the water works. And it seemed to him that it would be a poor thing to fail in what he had undertaken simply to save himself. As soon as he reached that conclusion he knew what he must do, or, at all events, what he must try to do.

For the officer who had arrested him he felt a good deal of contempt. While it was true that orders had to be obeyed, there was no reason, Harry felt, why the lieutenant should not have shown some discretion. An officer of the regular army would have done so, he felt. But this man looked unintelligent and stupid. Harry felt that he might safely rely on his appearance. And he was right. The officer found himself in a quandary at once. His men were mounted on cycles; Harry was on foot. And Harry saw that he didn't quite know what to do.

Finally he cut the Gordian knot, as it seemed to him, by impounding a bicycle from a passing wheel-man, who protested vigorously but in vain. All he got for his cycle was a scrap of paper, stating that it had been requisitioned for army use. And Harry was instructed to mount this machine and ride along between two of the territorial soldiers. He had been hoping for something like that, but had hardly dared to expect it. He had fully made up his mind now to take all the risks he would run by trying to escape. He could not get clear away, that much he knew. But now he, too, like Graves, needed a little time. He did not mind being recaptured in a short time if, in the meanwhile, he could be free to do what he wanted.

As to just how he would try to get away, he did not try to plan. He felt that somewhere along the route some chance would present itself, and that it would be better to trust to that than to make some plan. He was ordered to the front of the squad—so that a better eye could be kept upon him, as the lieutenant put it. Harry had irritated him by his attempts to cause a change in the disposition of Graves and himself, and the officer gave the impression now that he regarded Harry as a desperate criminal, already tried and convicted.

Harry counted upon the traffic, sure to increase as it grew later, to give him his chance. Something accidental, he knew, there must be, or he would not be able to get away. And it was not long before his chance came. As they crossed a wide street there was a sudden outburst of shouting. A runaway horse, dragging a delivery cart, came rushing down on the squad, and in a moment it was broken up and confused. Harry seized the chance. His bicycle, by a lucky chance, was a high geared machine and before anyone knew he had gone he had turned a corner. In a moment he threw himself off the machine, dragged it into a shop, ran out, and in a moment dashed into another shop, crowded with customers. And there for a moment, he stayed. There was a hue and cry outside. He saw uniformed men, on bicycles, dashing by. He even rushed to the door with the crowd in the shop to see what was amiss! And, when the chase had passed, he walked out, very calmly, though his heart was in his mouth, and quite unmolested got aboard a passing tram car.

He was counting on the stupidity and lack of imagination of the lieutenant, and his course was hardly as bold as it seems. As a matter of fact it was his one chance to escape. He knew what the officer would think—that, being in flight, he would try to get away as quickly as possible from the scene of his escape. And so, by staying there, he was in the one place where no one would think of looking for him!

On the tram car he was fairly safe. It happened, fortunately, that he had plenty of money with him. And his first move, when he felt it was safe, was to get off the tram and look for a cab. He found a taxicab in a short time, one of those that had escaped requisition by the government, and in this he drove to an outfitting shop, where he bought new clothes. He reasoned that he would be looked for all over, and that if, instead of appearing as a Boy Scout in character dress of the organization, he was in the ordinary clothes, he would have a better chance. He managed the change easily, and then felt that it was safe for him to try to get into communication with Dick.

In this attempt luck was with him again. He called for the number of the vicarage at Bray, only to find that the call was interrupted again at the nearest telephone center. But this time he was asked to wait, and in a moment he heard Jack Young's voice in his ear.

"We came over to explain about the wire's being cut," said Jack. "Dick's all right. He's here with me. Where are you? We've got to see you just as soon as we can."

"In London, but I'm coming down. I'm going to try to get a motor car, too. I'm in a lot of trouble, Jack—it's Graves."

"Come on down. We'll walk out along the road toward London and meet you. We've got a lot to tell you, but I'm afraid to talk about it over the telephone."

"All right! I'll keep my eyes open for you."

Getting a motor car was not easy. A great many had been taken by the government. But Harry remembered that one was owned by a business friend of his father's, an American, and this, with some difficulty, he managed to borrow. He was known as a careful driver. He had learned to drive his father's car at home, and Mr. Armstrong knew it. And so, when Harry explained that it was a matter of the greatest urgency, he got it—since he had established a reputation for honor that made Mr. Armstrong understand that when Harry said a thing was urgent, urgent it must be.

Getting out of London was easy. If a search was being made for him—and he had no doubt that that was true—he found no evidence of it. His change of clothes was probably what saved him, for it altered his appearance greatly. So he came near to Bray, and finally met his two friends.



CHAPTER XVI

THE CIPHER

"What happened to you?" asked Jack and Dick in chorus.

Swiftly Harry explained. He told of his arrest as a spy and of his escape. And when he mentioned the part that Ernest Graves had played in the affair, Jack and Dick looked at one another.

"We were afraid of something like that," said Jack. "Harry, we've found out a lot of things, and we don't know what they mean! We're sure something dreadful is going to happen to-night. And we're sure, too, that Bray Park is going to be the centre of the trouble."

"Tell me what you know," said Harry, crisply. "Then we'll put two and two together. I say, Jack, we don't want to be seen, you know. Isn't there some side road that doesn't lead anywhere, where I can run in with the car while we talk?"

"Yes. There's a place about a quarter of a mile further on that will do splendidly," he replied.

"All right. Lead the way! Tell me when we come to it. I've just thought of something else I ought never to have forgotten. At least, I thought of it when I took the things out of my pockets while I was changing my clothes."

They soon came to the turning Jack had thought of, and a run of a few hundred yards took them entirely out of sight of the main road, and to a place where they were able to feel fairly sure of not being molested.

Then they exchanged stories. Harry told his first. Then he heard of Dick's escape, and of his meeting with Jack. He nodded at the story they had heard from Gaffer Hodge.

"That accounts for how Graves knew," he said, with much satisfaction. "What happened then?"

When he heard of how they had thought too late of calling Colonel Throckmorton by telephone he sighed.

"If you'd only got that message through before Graves got in his work!" he said. "He'd have had to believe you then, of course. How unlucky!"

"I know," said Jack. "We were frightfully sorry. And then we went out to find where the wire was cut, and they got Dick. But I got away, and I managed to stay fairly close to them. I followed them when they left Dick in a little stone house, as a prisoner, and I heard this—I heard them talking about getting a big supply of petrol. Now what on earth do they want petrol for? They said there would still be plenty left for the automobiles—and then that they wouldn't need the cars any more, anyhow! What on earth do you make of that, Harry?"

"Tell me the rest, then I'll tell you what I think," said Harry. "How did you get Dick out? And did you hear them saying anything that sounded as if it might be useful, Dick?"

"That was fine work!" he said, when he had heard a description of Dick's rescue. "Jack, you seem to be around every time one of us gets into trouble and needs help!"

Then Dick told of the things he had overheard—the mysterious references to Von Wedel and to things that were to be done to the barracks at Ealing and Houndsditch. Harry got out a pencil and paper then, and made a careful note of every name that Dick mentioned. Then he took a paper from his pocket.

"Remember this, Dick?" he asked. "It's the thing I spoke of that I forgot until I came across it in my pocket this morning."

"What is it, Harry?"

"Don't you remember that we watched them heliographing some messages, and put down the Morse signs? Here they are. Now the thing to do is to see if we can't work out the meaning of the code. If it's a code that uses words for phrases we're probably stuck, but I think it's more likely to depend on inversions."

"What do you mean, Harry?" asked Jack. "I'm sorry I don't know anything about codes and ciphers."

"Why, there are two main sorts of codes, Jack, and, of course, thousands of variations of each of those principal kinds. In one kind the idea is to save words—in telegraphing or cabling. So the things that are likely to be said are represented by one word. For instance Coal, in a mining code, might mean 'Struck vein at two hundred feet level.' In the other sort of code, the letters are changed. That is done in all sorts of ways, and there are various tricks. The way to get at nearly all of them is to find out which letter or number or symbol is used most often, and to remember that in an ordinary letter E will appear almost twice as often as any other letter—in English, that is."

"But won't this be in German?"

"Yes. That's just why I wanted those names Dick heard. They are likely to appear in any message that was sent. So, if we can find words that correspond in length to those, we may be able to work it out. Here goes, anyhow!"

For a long time Harry puzzled over the message. He transcribed the Morse symbols first into English letters and found they made a hopeless and confused jumble, as he had expected. The key of the letter E was useless, as he had also expected. But finally, by making himself think in German, he began to see a light ahead. And after an hour's hard work he gave a cry of exultation.

"I believe I've got it!" he cried. "Listen and see if this doesn't sound reasonable!"

"Go ahead!" said Jack and Dick, eagerly.

"Here it is," said Harry. "'Petrol just arranged. Supply on way. Reach Bray Friday. Von Wedel may come. Red light markers arranged. Ealing Houndsditch Buckingham Admiralty War Office. Closing.'"

They stared at him, mystified.

"I suppose it does make sense," said Dick. "But what on earth does it mean, Harry?"

"Oh, can't you see?" cried Harry. "Von Wedel is a commander of some sort—that's plain, isn't it? And he's to carry out a raid, destroying or attacking the places that are mentioned! How can he do that? He can't be a naval commander. He can't be going to lead troops, because we know they can't land. Then how can he get here? And why should he need petrol?"

They stared at him blankly. Then, suddenly, Dick understood.

"He'll come through the air!" he cried.

"Yes, in one of their big Zeppelins!" said Harry. "I suppose she has been cruising off the coast. She's served as a wireless relay station, too. The plant here at Bray Park could reach her, and she could relay the messages on across the North Sea, to Helgoland or Wilhelmshaven. She's waited until everything was ready."

"That's what they mean by the red light markers, then?"

"Yes. They could be on the roofs of houses, and masked, so that they wouldn't be seen except from overhead. They'd be in certain fixed positions, and the men on the Zeppelins would be able to calculate their aim, and drop their bombs so many degrees to the left or the right of the red marking lights."

"But we've got aeroplanes flying about, haven't we?" said Jack. "Wouldn't they see those lights and wonder about them?"

"Yes, if they were showing all the time. But you can depend on it that these Germans have provided for all that. They will have arranged for the Zeppelin to be above the positions, as near as they can guess them, at certain times—and the lights will only be shown at those times, and then only for a few seconds. Even if someone else sees them, you see, there won't be time to do anything."

"You must be right, Harry!" said Jack, nervously. "There's no other way to explain that message. How are we going to stop them?"

"I don't know yet, but we'll have to work out some way of doing it. It would be terrible for us to know what had been planned and still not be able to stop them! I wish I knew where Graves was. I'd like—"

He stopped, thinking hard.

"What good would that do?"

"Oh, I don't want him—not just now. But I don't want him to see me just at present. I want to know where he is so that I can avoid him."

"Suppose I scout into Bray?" suggested Jack. "I can find out something that might be useful, perhaps. If any of them from Bray Park have come into the village to-day I'll hear about it."

"That's a good idea. Suppose you do that, Jack. I don't know just what I'll do yet. But if I go away from here before you come back, Dick will stay. I've got to think—there must be some way to beat them!"



CHAPTER XVII

A CAPTURE FROM THE SKIES

Jack went off to see what he could discover, and Harry, left behind with Dick, racked his brain for some means of blocking the plan he was so sure the Germans had made. He was furious at Graves, who had discredited him with Colonel Throckmorton, as he believed. He minded the personal unpleasantness involved far less than the thought that his usefulness was blocked, for he felt that no information he might bring would be received now.

As he looked around it seemed incredible that such things as he was trying to prevent could even be imagined. After the early rain, the day had cleared up warm and lovely, and it was now that most perfect of things, a beautiful summer day in England. The little road they had taken was a sort of blind alley. It had brought them to a meadow, whence the hay had already been cut. At the far side of this ran a little brook, and all about them were trees. Except for the calls of birds, and the ceaseless hum of insects, there was no sound to break the stillness. It was a scene of peaceful beauty that could not be surpassed anywhere in the world. And yet, only a few miles away, at the most, were men who were planning deliberately to bring death and destruction upon helpless enemies—to rain down death from the skies.

By very contrast to the idyllic peace of all about them, the terrors of war seemed more dreadful. That men who went to war should be killed and wounded, bad though it was, still seemed legitimate. But this driving home of an attack upon a city all unprepared, upon the many non-combatants who would be bound to suffer, was another and more dreadful thing. Harry could understand that it was war, that it was permissible to do what these Germans planned. And yet—

His thoughts were interrupted by a sudden change in the quality of the noisy silence that the insects made. Just before he noticed it, half a dozen bees had been humming near him. Now he heard something that sounded like the humming of a far vaster bee. Suddenly it stopped, and, as it did, he looked up, his eyes as well as Dick's being drawn upward at the same moment. And they saw, high above them, an aeroplane with dun colored wings. Its engine had stopped and it was descending now in a beautiful series of volplaning curves.

"Out of essence—he's got to come down," said Harry, appraisingly, to Dick. "He'll manage it all right, too. He knows his business through and through, that chap."

"I wonder where he'll land," speculated Dick.

"He's got to pick an open space, of course," said Harry. "And there aren't so many of them around here. By Jove!"

"Look! He's certainly coming down fast!" exclaimed Dick.

"Yes—and, I say, I think he's heading for this meadow! Come on—start that motor, Dick!"

"Why? Don't you want him to see us?"

"I don't mind him seeing us—I don't want him to see the car," explained Harry. "We'll run it around that bend, out of sight from the meadow."

"Why shouldn't he see it?"

"Because if he's out of petrol he'll want to take all we've got and we may not want him to have it. We don't know who he is, yet."

The car was moving as Harry explained. As soon as the meadow was out of sight Harry stopped the engine and got out of the car.

"He may have seen it as he was coming down—the car, I mean," he said. "But I doubt it. He's got other things to watch. That meadow for one—and all his levers and his wheel. Guiding an aeroplane in a coast like that down the air is no easy job."

"Have you ever been up, Harry?"

"Yes, often. I've never driven one myself, but I believe I could if I had to. I've watched other people handle them so often that I know just about everything that has to be done."

"That's an English monoplane. I've seen them ever so often," said Dick. "It's an army machine, I mean. See its number? It's just coming in sight of us now. Wouldn't I like to fly her though?"

"I'd like to know what it's doing around here," said Harry. "And it seems funny to me if an English army aviator has started out without enough petrol in his tank to see him through any flight he might be making. And wouldn't he have headed for one of his supply stations as soon as he found he was running short, instead of coming down in country like this?"

Dick stared at him.

"Do you think it's another spy?" he asked.

"I don't think anything about it yet, Dick. But I'm not going to be caught napping. That's a Bleriot—and the British army flying corps uses Bleriots. But anyone with the money can buy one and make it look like an English army 'plane. Remember that."

There was no mistake about that monoplane when it was once down. Its pilot was German; he was unmistakably so. He had been flying very high and when he landed he was still stiff from cold.

"Petrol!" he cried eagerly, as he saw the two boys. "Where can I get petrol? Quick! Answer me!"

Harry shot a quick glance at Dick.

"Come on," he said, beneath his breath. "We've got to get him and tie him up."

The aviator, cramped and stiffened as he was by the intense cold that prevails in the high levels where he had been flying, was no match for them. As they sprang at him his face took on the most ludicrous appearance of utter surprise. Had he suspected that they would attack him he might have drawn a pistol. As it was, he was helpless before the two boys, both in the pink of condition and determined to capture him. He made a struggle, but in two minutes he was lying roped, tied, and utterly helpless. He was not silent; he breathed the most fearful threats as to what would happen to them. But neither boy paid any attention to him.

"We've got to get him to the car," said Harry. "Can we drag him?"

"Yes. But if we loosened his feet a little, he could walk," suggested Dick. "That would be ever so much easier for him, and for us, too. I should hate to be dragged. Let's make him walk."

"Right—and a good idea!" said Harry. He loosened the ropes about the aviator's feet, and helped him to stand.

"March!" he said. "Don't try to get away—I've got a leading rope, you see."

He did have a loose end of rope, left over from a knot, and with this he proceeded to lead the enraged German to the automobile. It looked for all the world as if he were leading a dog, and for a moment Dick doubled up in helpless laughter. The whole episode had its comic side, but it was serious, too.

"Now we've got to draw off the gasoline in the tank in this bucket," said Harry. The German had been bestowed in the tonneau, and made as comfortable as possible with rugs and cushions. His feet were securely tied again, and there was no chance for him to escape.

"What are you going to do?" asked Dick. "Are you going to try to fly in that machine?"

"I don't know, yet. But I'm going to have it ready, so that I can if I need to," said Harry. "That Bleriot may be the saving of us yet, Dick. There's no telling what we shall have to do."

Even as he spoke Harry was making new plans, rendered possible by this gift from the skies. He was beginning, at last, to see a way to circumvent the Germans. What he had in mind was risky, certainly, and might prove perilous in the extreme. But he did not let that aspect of the situation worry him. His one concern was to foil the terrible plan that the Germans had made, and he was willing to run any risk that would help him to do so.

"That Zeppelin is coming here to Bray Park—it's going to land here," said Harry. "And if it ever gets away from here there will be no way of stopping it from doing all the damage they have planned, or most of it. Thanks to Graves, we wouldn't be believed if we told what we knew—we'd probably just be put in the guard house. So we've got to try to stop it ourselves."

They had reached the Bleriot by that time. Harry filled the tank, and looked at the motor. Then he sat in the driver's seat and practiced with the levers, until he decided that he understood them thoroughly. And, as he did this, he made his decision.

"I'm going into Bray Park to-night," he said. "This is the only way to get in."

"And I'm going with you," announced Dick.



CHAPTER XVIII

VINDICATION

At first Harry refused absolutely to consent to Dick's accompanying him, but after a long argument he was forced to yield.

"Why should you take all the risks when it isn't your own country, especially?" asked Dick, almost sobbing. "I've got a right to go! And, besides, you may need me."

That was true enough, as Harry realized. Moreover, he had been investigating the Bleriot, and he discovered that it was one of a new safety type, with a gyroscope device to insure stability. The day was almost without wind, and therefore it seemed that if such an excursion could ever be safe, this was the time. He consented in the end, and later he was to be thankful that he had.

Once the decision was taken, they waited impatiently for the return of Jack Young. Harry foresaw protests from Jack when he found out what they meant to do, but for him there was an easy answer—there was room in the aeroplane for only two people, and there was no way of carrying an extra passenger.

It was nearly dusk when Jack returned, and he had the forethought to bring a basket of food with him—cold chicken, bread and butter, and milk, as well as some fruit.

"I didn't find out very much," he said, "except this. Someone from London has been asking about you both. And this much more—at least a dozen people have come down to Bray Park to-day from London."

"Did you see any sign of soldiers from London?"

"No," said Jack.

He was disappointed when he found out what they meant to do, but he took his disappointment pluckily when he saw that there was no help for it. Harry explained very quietly to both Jack and Dick what he meant to do and they listened, open mouthed, with wonder.

"You'll have your part to play, Jack," said Harry. "Somehow I can't believe that the letter I wrote to Colonel Throckmorton last night won't have some effect. You have got to scout around in case anyone comes and tell them all I've told you. You understand thoroughly, do you?"

"Yes," said Jack, quietly. "When are you going to start?"

"There's no use going up much before eleven o'clock," said Harry. "Before that we'd be seen, and, besides, if a Zeppelin is coming, it wouldn't be until after that. My plan is to scout to the east and try to pick her up and watch her descend. I think I know just about where she'll land—the only place where there's room for her. And then—"

He stopped, and the others nodded, grimly.

"I imagine she'll have about a hundred and twenty miles to travel in a straight line—perhaps a little less," said Harry. "She can make that in about two hours, or less. And she'll travel without lights, and in the dark. Big as they are, those airships are painted so that they're almost invisible from below. So if she comes by night, getting here won't be as hard a job as it seems at first thought."

Then the three of them went over in every detail the plan Harry had formed. Dick and Harry took their places in the monoplane and rehearsed every movement they would have to make.

"I can't think of anything else that we can provide for now," said Harry, at last. "Of course, we can't tell what will come up, and it would be wonderful if everything came out just as we had planned. But we've provided for everything we can think of. You know where you are to be, Jack?"

"Yes."

"Then you'd better start pretty soon. Good-bye, Jack!" He held out his hand. "We could never have worked this out without you. If we succeed you'll have had a big part in what we've done."

A little later Jack said good-bye in earnest, and then there was nothing to do but wait. About them the voices of the insects and frogs changed, with the darkening night. The stars came out, but the night was a dark one. Harry looked at his watch from time to time and at last he got up.

"Time to start!" he said.

He felt a thrill of nervousness as the monoplane rose in the air. After all, there was a difference between being the pilot and sitting still in the car. But he managed very well, after a few anxious moments in the ascent. And once they were clear of the trees and climbing swiftly, in great spirals, there was a glorious sensation of freedom. Dick caught his breath at first, then he got used to the queer motion, and cried aloud in his delight.

Harry headed straight into the east when he felt that he was high enough. And suddenly he gave a cry.

"Look!" he shouted in Dick's ear. "We didn't start a moment too soon. See her—that great big cigar-shaped thing, dropping over there?"

It was the Zeppelin—the battleship of the air. She was dipping down, descending gracefully, over Bray Park.

"I was right!" cried Harry. "Now we can go to work at once—we won't have to land and wait!"

He rose still higher, then flew straight for Bray Park. They were high, but, far below, with lights moving about her, they could see the huge bulk of the airship, as long as a moderate sized ocean liner. She presented a perfect target.

"Now!" said Harry.

And at once Dick began dropping projectiles they had found in the aeroplane—sharply pointed shells of steel. Harry had examined these—he found they were really solid steel shot, cast like modern rifle bullets, and calculated to penetrate, even without explosive action, when dropped from a height.

From the first two that Dick dropped there was no result. But with the falling of the third a hissing sound came from below, and as Dick rapidly dropped three more the noise increased. And they could see the lights flying—plainly the men were running from the monster. Its bulk lessened as the gas escaped from the great bag and then, in a moment more, there was a terrific explosion that rocked the monoplane violently. Had Harry not been ready for it, they might have been brought down.

But he had been prepared, and was flying away. Down below there was now a great glare from the burning wreckage, lighting up the whole scene. And suddenly there was a sharp breaking out of rifle fire. At first he thought the men below had seen them, and were firing upward. But in a moment he saw the truth. Bray Park had been attacked from outside!

Even before they reached the ground, in the meadow where Harry and Jack had emerged from the tunnel, the firing was over. But now a search-light was playing on the ground on the opposite bank, and Harry and Dick saw, to their wonder and delight, that the ground swarmed with khaki-clad soldiers. In the same moment Jack ran up to them.

"The soldiers had the place surrounded!" he cried, exultingly. "They must have believed your letter after all, Harry! Come on—there's a boat here! Aren't you coming over?"

They were rowing for the other shore before the words were well spoken. And, once over, they were seized at once by two soldiers.

"More of them," said one of the soldiers. "Where's the colonel?"

Without trying to explain, they let themselves be taken to where Colonel Throckmorton stood near the burning wreckage. At the sight of Harry his face lighted up.

"What do you know about this?" he asked, sternly, pointing to the wrecked airship.

Harry explained in a few words.

"Very good," said the colonel. "You are under arrest—you broke arrest this morning. I suppose you know that is a serious offence, whether your original arrest was justified or not?"

"I felt I had to do it, sir," said Harry. He had caught the glint of a smile in the colonel's eyes.

"Explain yourself, sir," said the colonel. "Report fully as to your movements to-day. Perhaps I shall recommend you for a medal instead of court martialling you, after all."

And so the story came out, and Harry learned that the colonel had never believed Graves, but had chosen to let him think he did.

"The boy Graves is a German, and older than he seems," said the colonel. "He was here as a spy. He is in custody now, and you have broken up a dangerous raid and a still more dangerous system of espionage. If you hadn't come along with your aeroplane, we would never have stopped the raid. I had ordered aviators to be here, but it is plain that something has gone wrong. You have done more than well. I shall see to it that your services are properly recognized. And now be off with you, and get some sleep. You may report to me the day after to-morrow!"

THE END