Davis, it could be plainly seen, was furiously angry; but he held himself in check, apparently realizing that victory depended upon coolness and caution.

Frank advanced swiftly, swung and missed by a fraction of an inch, as Davis jerked his head sharply to one side. Before the lad could recover, Davis struck out viciously and landed flush on Frank's jaw. The lad staggered back, but before Davis could follow up his advantage, Frank covered and held his opponent off. The blow had been the hardest of the fight so far.

Davis, with more confidence since this blow, stepped forward aggressively, feinted quickly two or three times, and sent a hard right to Frank's sore jaw. Again Frank covered up and gave ground. Believing that he had the lad at his mercy, Davis advanced quickly and swung hard with his left.

With dazzling rapidity, Frank stepped inside and, catching the swing with his left arm, planted his right fist squarely upon Davis' nose. Davis uttered a cry of pain and leaped back. Frank followed, pressing him closely.

Davis seemed content to remain on the defensive now, and for the space of perhaps a minute warded off all the lad's blows with a really remarkable defense. Even Jack was forced to give him his due.

"He can box," he muttered, "but I doubt if he can keep his head."

But the end of the battle came now with sudden and unexpected swiftness. Frank, seeking to put an end to the fight, stepped forward, feinted with his left, and drove his right straight for Davis' chin, swinging from the floor.

Davis jerked his head back sharply, and the lad missed. Before he could recover Davis had swung hard with both hands and both blows went home, one catching Frank in the abdomen, doubling him up, and the other straightening him again as it landed squarely on his chin.

Frank dropped to the floor and lay still.



CHAPTER XVIII.

MISTAKEN FOR AN ENEMY.

Davis had won—fairly and cleanly—there was no doubt about that.

But Jack and Lord Hastings wasted no time in considering the merits of the encounter. Each sprang forward and bent above the lad. Lord Hastings raised the boy's head to his knee.

"Water," he said to Jack.

The latter hastened to get it, and after a few drops had been sprinkled over his face, Frank opened his eyes. He glanced up curiously at Lord Hastings.

"What's the matter?" he asked. "What's happened?"

"Matter is," returned Jack quietly, "that you have just been convinced that you are not such a terrible fighter as you have been thinking."

"You mean he licked me?" demanded Frank, suddenly realizing just what had happened.

"He did," returned Jack dryly; "and he did a pretty good job of it."

"But I tell you I had him," cried Frank. "One more blow and—and——"

"The one more blow didn't land," replied his chum.

"But I tried——"

"Yes, you tried, all right. I saw you. You just missed him and then he landed on you—twice, and hard. That's why you're here."

"He couldn't do it again," said Frank feebly.

"Maybe not and maybe yes," said Jack. "However, you're not going to have another trial. You've been licked, and licked good and proper, and that's all there is to it. See if you can get up now. I'll take you to our own quarters."

Frank pulled himself to his feet, and, leaning on Jack, walked from the room.

Davis now had donned his coat and stood near as the two passed out. There was a sneering smile on his puffed face, and he spoke.

"Perhaps you fellows will pay a little more attention to me when I say something after this," he muttered.

Jack whirled on him sharply.

"See here," he said quietly, "if you make any trouble in the future I'll take you in hand myself. You'll find that the result will be somewhat different."

"So?" sneered Davis, feeling not a little proud of himself. "You are at liberty to try at any time. Right now, eh?"

He made as if to discard his coat. Flushed with victory, he manifested no doubt that he could handle Jack as well as Frank.

In spite of himself, Jack was forced to smile.

"We won't fight now," he said quietly. "You're not in condition in the first place. But when you have been fixed up, I just want to tell you not to trifle with me."

"Threats, eh?"

"Call them what you please. I don't want to have to spank you, but I may have to. Don't bother me, that's all."

He helped Frank from the room without another word. Lord Hastings, about to leave the room, stopped for a word with Davis.

"Just a word of advice," he said. "As you know, we are on a perilous duty. Any more trouble and I'll have you ironed if necessary. You're in no position to make a nuisance of yourself."

Davis made no reply. He recognized Lord Hastings' authority to do as he said and he was smart enough to say nothing. Lord Hastings left Davis with the sailors.

An hour after leaving the spot where the U-16 had so recently sent a German submarine to the bottom, Lord Hastings again gave the command to come to the surface; and the vessel proceeded then upon the top of the water.

Frank and Jack, tired out, had retired for a brief rest before their services would again be required; but had they been in Davis' cabin they would have overheard a strange conversation.

Davis and three of the German sailors were engaged in a deep and apparently serious discussion. They talked in subdued tones and cast occasional furtive glances at the door. Occasionally the three nodded their heads affirmatively as Davis talked, each occasionally volunteering a few words himself.

"Then you are with me?" asked Davis at length.

The men nodded.

"Good. But we shall have to bide our time. A false step and it would be the end of all of us. This Commander Bernstorff, I should say, is a bad man to fool with. But once we can get him in our power and silence the others, we can make something of ourselves."

"Yah!" muttered one of the sailors. "What is this war to us anyhow? You are English and we are German; but what of it? Why should we take orders from such men as Herr Commander Bernstorff and others of his kind?"

"Why, indeed?" echoed another.

"You are right," said Davis. "Now, when we take possession of this vessel we will be our own masters. No one to tell us what to do. We won't have to risk our lives for some one else's gain. And what booty we can get shall be evenly divided among us. There is rich prey upon the sea."

"But first," said one of the sailors, "to come into possession of this vessel, we shall have to dispose of Commander Bernstorff, his lieutenants, and others of the crew."

"How," exclaimed one of the others suddenly, "how if some of the others would join us? I have no doubt they would if approached in the right way."

"We don't want too many," protested the third. "The fewer of us, the fewer to share in the spoils."

"True enough," said Davis, "but we must have men enough for a crew. I, of course, shall command. You three will be my officers. We must have a crew."

"How about the English sailors?" asked one of the Germans. "They must be dissatisfied. Here they are prisoners and will be kept under guard until the end of the war. Certainly they should be willing to join us. It will mean freedom and a share in the rich spoils."

"With which to retire when the war is over," put in another. "Why, we can go to America and live at ease for years to come."

"Which is my plan exactly," declared Davis. "Yes, we must have a crew. Hans, do you think you could approach these prisoners?"

"Leave that to me, sir," replied Hans with an evil wink. "I think I can convince them, sir."

"Good; but in the meantime, do not talk this among yourselves. I believe we had better wait until after the end of the expedition we are now on. Vigilance, probably, will relax then. In the meantime, we must try and show ourselves to be perfectly loyal to the Kaiser."

"Very well, sir."

"All right then," said Davis. "You fellows clear out now. I want to get a little sleep."

Silently the three conspirators made their way from the traitor's cabin. No one saw them go and the success of the plot seemed assured as the U-16 continued on her journey, Lord Hastings, Frank, Jack and the other British aboard unaware and unsuspecting.

Shortly after dusk of the night upon which the German under-sea fleet expected to spring its coup, the U-16 lay upon the calm surface of the water still some distance from the point set for the gathering of the submarine flotilla at the midnight hour, and likewise a considerable distance from Dover.

Explaining his reason for stopping here, Lord Hastings said: "There may be British patrol boats about—probably are. I want you boys to remain in charge here, while I take a boat and try to reach the British authorities."

"One of us had better go along, sir," declared Frank.

Lord Hastings considered this a minute.

"I don't know but you are right," he finally said. "Frank shall go. Jack will take command in my absence."

He addressed the latter. "Arm Edwards and our other men," he continued, "though do it unknown to the Germans. I don't altogether trust this Davis. Of course he is in the pay of the Germans; but once a traitor always a traitor. Watch him closely."

"I'll watch him," said Jack quietly.

"Very well. Frank and I shall leave at once."

Lord Hastings ordered a small boat over the side, the two jumped into it and rowed rapidly away, leaving Jack to pass the word among the crew that Commander Bernstorff had gone on a little scouting expedition.

For half an hour Lord Hastings and Frank rowed along without incident until they could see a few dull lights in the distant town of Dover.

"Seems to me there is a terrible lack of vigilance hereabouts," declared Frank.

"It does look that way," Lord Hastings admitted. "However——"

There came a sudden interruption—the sound of a shot, and a bullet whistled overhead.

"Not such a terrible lack of vigilance, either," remarked Lord Hastings. "I wonder where that shot came from?"

He gazed about but could see nothing in the darkness. Came a second shot from behind him, and turning, the two saw a little motorboat that had crept up behind them unnoticed.

"We surrender!" called Lord Hastings, fearing to take a chance that the next shot would miss.

The motorboat came toward them quickly.

"Who are you?" demanded a figure standing in the bow, and at this distance Lord Hastings could dimly make out that the man wore a British uniform.

"Friends," was the reply.

The British officer peered at them sharply, then noticed their German uniforms.

"Friends, eh," he said; "in those uniforms. Not likely. Climb into my boat."

Lord Hastings and Frank obeyed without a word, and at a command from the British officer the motorboat put about and headed shoreward.

"Where are you taking us?" asked Lord Hastings quietly.

"None of your business," was the sharp response.

"So?" said Lord Hastings quietly. "I would advise you to speak more respectfully. I would not like to report you. I asked you a civil question and I would appreciate a civil answer."

"Well, I'll tell you, seeing that you are so anxious," replied the officer. "I am taking you to Admiral Fischer, at Dover, who, most likely, will know better how to attend to your case than I do."

"Most likely," repeated Lord Hastings. "And how long before we may expect to see the admiral?"

"About half an hour."

"Good!" And Lord Hastings whispered to Frank: "Plenty of time. Fortunately I am well acquainted with Admiral Fischer."



CHAPTER XIX.

THE TRAP IS SET.

"Hastings!"

The exclamation was wrung from the lips of the astonished Admiral Fischer, in command of the naval forces operating about Dover.

"Right you are, Fischer," was Lord Hastings' smiling rejoinder, "though how you recognized me in all this German toggery is more than I can explain."

The admiral advanced and wrung Lord Hastings' hand.

"And why this German uniform?" he asked. "And who is this young man with you?"

"I'll answer the last question first," smiled Lord Hastings, "by presenting to your excellency, my second officer, Mr. Frank Chadwick."

Admiral Fischer acknowledged the introduction.

"Now for the answer to my other question," he said.

In a few brief words Lord Hastings explained. As he progressed with his recital Admiral Fischer became more and more astonished. And when Lord Hastings had concluded, the admiral burst out:

"And you mean to tell me the Germans have the temerity to attempt a raid in the very mouth of the Thames?"

Lord Hastings nodded.

"They certainly have," he said quietly, and he produced the order he had received from the German admiral.

Admiral Fischer scanned it closely.

"It's authentic enough," he said finally, "I know his signature well. And this raid is to take place at midnight, eh?"

"Well, no. We are to gather at midnight. How long it will take to reach the mouth of the Thames you can figure yourself."

"I can," declared the admiral. "And I can also figure that if these submarines dare enter the Thames they will never get out."

"But you must figure better than that, Admiral. You must figure so they will be unable to do any damage. That's even better than figuring that they cannot escape after the damage is done."

"So it is," returned the admiral. "Have you a plan?"

"Why, yes! You must immediately order all warships and other craft now at the mouth of the Thames, further up river. Order a swift torpedo boat flotilla down the river—as many as are available—and have half a dozen torpedo boats—equipped with nets—to take their places behind the motorboat fleet."

"And then?"

"Well, the motorboats will attack the submarines as soon as they appear. A few of them undoubtedly will be sunk. Then let the rest retire. The submarines, submerged by this time, will travel forward a bit. At this point have the torpedo boats, with nets stretched, proceed down each side of the river. Of course, the torpedo boats must advance at the moment the motorboats flee."

"But I should think the Germans are too wary to be caught in a trap like that."

"They won't be, because they expect the raid to be too unexpected for such details to have been arranged. Only one stipulation. Instruct all your officers under no circumstances to fire at the first submersible to move up the river."

"And why?" demanded the admiral.

"Chiefly," smiled Lord Hastings, "because I don't want to go to the bottom."

"Oh, I see! You mean to lead the German advance."

"Exactly, and for two reasons. First, because I wish to reach a place of safety at the earliest possible moment, and second, because if the Germans see one craft advance, apparently unafraid, the others will not hesitate to follow."

"But perhaps it will be impossible for you to lead the way."

"You just leave that to me, Fischer. I shall be in the first submarine. The only question that remains is whether you have time to lay your plans."

"Plenty," was the reply. "I'll begin now."

He pressed a button on his desk and an orderly entered. At a command he left the room again, only to summon other officers. Admiral Fischer scribbled rapidly, passing paper after paper to different officers. At the end of another half hour, he turned to Lord Hastings.

"All ready," he said quietly.

"You have lost no time," replied Lord Hastings with a smile. He glanced at his watch. "Almost ten," he said. "Come, Frank, we shall have to hurry."

"Look here, Hastings," said Admiral Fischer, "don't you think you are taking unnecessary risks? What's the use of going back? Why not stay here?"

"Impossible, Fischer," returned Lord Hastings. "In the first place, some of my men are there and I must return to them. Then again, I want to be in the fun."

The admiral shrugged his shoulders.

"I know you too well to insist," he said. "So be it. But one thing; remember that you must be in the first submarine."

"I'll be there," said Lord Hastings.

Admiral Fischer summoned the officer who had conducted the two to him and instructed him to return them to where he had picked them up. The officer looked surprised, but he said nothing. Lord Hastings shook hands with Admiral Fischer and he and Frank followed the officer from the room.

Quickly they made their way back to the motorboat, were hurried out over to the dark water, and finally were given their own small boat again, in which they headed for the U-16.

"Think you can find her, sir?" asked Frank.

"No trouble at all," was the reply.

And there was no trouble.

By eleven o'clock they were safely back aboard and Jack received them anxiously.

"What luck, sir?" he asked.

"Excellent," replied Lord Hastings. "How did everything go in my absence?"

"All quiet, sir."

"No trouble with Davis?"

"No, sir. I haven't even seen him."

"Very well. Now you may give the order to submerge and we'll make for the rendezvous."

Jack obeyed.

It was just exactly three minutes to twelve when Lord Hastings, having taken his bearings and found he was in the designated spot, gave the command to come to the surface.

Slowly the U-16 arose from the deep, and immediately she rested upon the surface, Jack and Frank followed Lord Hastings to the bridge.

The night was perfectly dark and at first they were unable to make out an object upon the silent water. But suddenly, to the left, there was a single brief flash of light; a second to the right; one forward and one astern; then other arrivals from the deep flashed a signal of their safe arrival. Producing his small pocket flashlight, Lord Hastings did the same.

"Seven besides ourselves," he muttered to himself.

Slowly now the submarines drew closer together until presently a voice from the bridge of one could be heard by all as Admiral Schuler addressed his captains.

"We shall submerge until our periscopes alone show," he gave his orders. "Then we shall proceed at full speed for the mouth of the Thames."

"But mines?" protested a voice.

"The mines have been swept clear," was the reply. "A flotilla of mine sweepers have been busy since dark. Now, heed these orders: We shall keep as close together as possible. Reaching the Thames, one submarine must lead the way. I shall call for a volunteer."

"Here, sir," Lord Hastings spoke up before the other commanders had a chance.

The others also volunteered, but Admiral Schuler awarded the honor to the U-16.

"You spoke first," he explained. Then he continued: "Unfortunately, we have been unable to learn the exact positions of the various British war vessels in the Thames, but we do know that there are many stationed there—just how far up the river I cannot say. However, once there we shall not return until we have sunk them."

A subdued cheer ran across the water in the darkness.

"It is time to go," said Admiral Schuler. "I shall show the way to the Thames, when the U-16 will take the lead. To your posts and follow me closely."

He went below, and the other commanders did likewise. A moment later the purr of machinery became audible aboard each vessel. Each submerged until the tip of her periscope protruded above the water, and then they sped after the flagship into the darkness of the night.

Swiftly they went, for Admiral Schuler realized the value of haste. He wished to make the raid and be out to sea again before the break of day.

Aboard the eight units of the submarine flotilla there was joy unrestrained. The crews of each vessel had been taken into the confidence of their commanders by this time and the men aboard seven of the craft were eagerly awaiting the moment when they could strike a terrible blow at the British navy. In view of the successes that had already attended the efforts of the German submersibles, there was little doubt in the hearts of the men that the present venture would be accomplished.

Even the three British sailors aboard the U-16 were cheerful, for although they did not realize the exact import of their mission, they knew Lord Hastings well enough to realize that he was acting in this manner only because there was some big duty to perform. They were content to follow him blindly.

Perhaps the only four men with the fleet who did not really have their interests aroused were Davis and his three fellow conspirators. Their only hope was that the sooner they came through the venture successfully the sooner they might get to work on their own plans.

The submarine fleet sped silently through the waters, going as swift as the wind; and when it finally reached the broad mouth of the Thames, the key to London itself, it still lacked two hours of dawn. But it was time for quick work and Admiral Schuler was not the man to hesitate—had he been, he would not have held this important post.

The submarines came to the surface now, in accordance with previous instructions, and Admiral Schuler, by a signal with his light, instructed the U-16 to proceed ahead. The other vessels dropped back a little.

"Well," said Lord Hastings to Frank and Jack, who stood beside him on the bridge, "here goes. May good fortune attend us."

He gave Jack the command:

"Full speed ahead!"



CHAPTER XX.

THE TRAP IS SPRUNG.

As the three officers aboard the U-16 knew, British battleships and vessels of war of all descriptions had been stationed all along the Thames, many of them patrolling the very mouth of the river. But now, as Lord Hastings, Jack and Frank stood upon the bridge of the little submarine after it had entered the mouth of Thames, there was not a vessel of any kind to be seen in the darkness.

"Admiral Fischer's orders have been followed out, sir," said Jack in a low voice.

Lord Hastings nodded but made no reply.

Behind the U-16 the other German submarines followed closely, two abreast. Aboard each the men stood to their posts, awaiting the signal they expected at any minute. All the vessels moved along upon the surface. The officers, from their places upon the bridge, followed with their eyes the movements of the U-16, which displayed a small stern light to guide them on.

In case of danger Lord Hastings had been instructed to give immediate warning, that the vessels behind might have time to dive.

Perhaps a hundred yards away in the darkness Frank's keen eyes now made out the forms of many little craft approaching them silently and swiftly. He immediately called Lord Hastings' attention.

"The motorboats," replied the latter quietly. "Things are working out just right."

Behind the motorboat flotilla could be seen forms of larger and mightier ships of war—the torpedo boats which were advancing in the wake of the mosquito fleet to surround the enemy submarines and capture or sink them. They came along close to the shore on either side of the river and the U-16 continued up the river in the exact center.

"When we get by, they'll close in," said Lord Hastings.

But now one of the commanders with the motorboat flotilla could restrain his impatience no longer, and while still some distance from the enemy gave the command to fire.

A single big gun boomed in the darkness and a shell screamed over the U-16 toward the German submarines beyond.

"The fool!" exclaimed Lord Hastings angrily. "Why could he not wait? There is no reason for concealment longer."

Immediately he gave the signal agreed upon with the German admiral, the darkening of the tail light—the signal for the others to submerge—and the U-16 dashed forward faster than before—to reach a place of safety as quickly as possible and to get out of range of the British ships, which, a moment later, opened upon the enemy with every available gun.

Directly opposite the U-16 there was a terrible explosion, a blinding flash, illumining the night like day. A German submarine had launched a torpedo and it had gone home. The foremost British torpedo boat had been destroyed.

But the others rushed on.

The Germans had heeded Lord Hastings' signal to submerge and were doing their best to disappear beneath the water before the British could reach them, the while firing an occasional torpedo, in the hope that it would go true, for they were unable to find the range and were working on mere guesswork.

Before the first of the foe could submerge a shell from one of the little motorboats struck her squarely upon the bridge, killing the captain and other officers, and shattering the conning tower. The men below no longer had a means of guiding the vessel, which drifted toward her nearest neighbor and rammed her amidships. This blow, while not necessarily fatal, threw the latter out of her stride, and being unable to tell for the moment what was wrong, the German commander gave the order to cease submerging; and the vessel remained where she was until a shell from a British torpedo boat put an end to her.

The two enemy under-sea boats last in line had turned about with the first warning and were making full speed down river again. The rest had submerged before the British could come upon them and had sought to come about and make their way to safety beneath the water.

But the British vessels were too swift for them. With mine nets stretched clear across the river, now that the U-16 had passed to safety, the torpedo boats dashed ahead; and an hour later four more German submarines, caught in these powerful nets, were helpless. It only remained to drag them to the surface and make prisoners of the crews, which work was deferred until daylight.

Aboard the U-16 none knew what had occurred save the three upon the bridge—Lord Hastings, Frank and Jack. Below, all stood to their posts, awaiting they knew not what.

Jack descended.

"All right, men," he said, "you may turn in, if you wish. There'll be no fighting to-night."

There was an exclamation of disappointment from among the German sailors, who apparently had been banking on dealing a severe blow to the British. There were several questions, which Jack answered by saying:

"We haven't come upon the enemy yet, and will not to-day."

He returned to the bridge.

"I suppose," said Lord Hastings, "the best thing we can do now is to go ashore and report. Frank, you shall come with me. Jack will remain behind."

The lads nodded.

Half an hour later Jack was left aboard the U-16, while Lord Hastings and Frank were being rowed ashore.

Below, although Jack did not know it, trouble was brewing. Davis and his three fellow-conspirators were plotting again.

"And what did this man Edwards say?" demanded Davis of one of the Germans.

"He said he would let me know some time to-day," was the reply. "Also, that he felt sure the others would follow his lead—would do whatever he said. He agreed with me that this was no war of ours, and added that as long as kings and emperors were using us to do their will, there was no reason why we shouldn't confiscate the property of kings and emperors to gain a few advantages for ourselves."

"By Jove!" exclaimed Davis. "The fellow reasons well. He may prove the very man for us." And he added to himself: "It would be a good thing to have another Englishman with me, if he is of the right sort."

The conversation continued for some moments, and then Davis said:

"Say, one of you fellows, tell Edwards I want to see him now."

One of the men departed, and returned a moment later, followed by Edwards. Davis engaged him in conversation and the two talked in low tones for perhaps five minutes. Then Davis turned to the others.

"I can see no reason why we should wait longer," he said. "Bernstorff and one of his officers is ashore. There remains only one and the crew. We can dispose of the one officer easily enough, and as for the crew, I am of the opinion that most of them will join us."

"Then," said Edwards, "if you will wait here until I return I will get my other men."

"It would be better that way," agreed Davis. "There will be seven of us and that should be enough. Hurry."

Edwards withdrew. First he made his way to where O'Brien and McDonald were asleep, and, rousing them, bade them follow him; but instead of returning to Davis' quarters, he led the way rapidly to where Jack stood upon the bridge.

Edwards explained the situation in a few brief words and Jack was dumbfounded.

"And you say Davis is preparing to spring this coup to-night?" exclaimed Jack.

"Right now, sir," returned Edwards quietly. "That's why I brought O'Brien and McDonald here. We are all armed, sir."

"Oh, we are more than a match for Davis and his trio of conspirators," Jack agreed. "The only thing that troubles me is that the others of the crew may join him. We shall have to act quickly. Follow me."

He drew his revolver and led the way below. There he hurried straight to Davis' quarters and flung open the door. Then he stopped in surprise.

"No one here," he ejaculated.

He was right. Davis and the others had gone; and though Jack did not know it, they were at that moment aft haranguing the crew, who had gathered about them eagerly.

Every man aboard the ship was now armed, for Lord Hastings had decided it would be inadvisable to relieve them of their weapons—it would have aroused their suspicions—and they were receiving Davis' proposals with satisfaction. It seemed that they had long harbored such thoughts and all that had been needed to egg them on had been a leader. They seemed to have found one in Davis.

"Then you men are with me?" asked Davis, his face flushed with pleasure.

The answer was a cheer; and the cheer carried to Jack, who was still in Davis' quarters. It told the lad what had happened just as well as though he had been present and overheard the conversation.

"Quick men! Back to the bridge!" the lad exclaimed.

He dashed forward, but he was not quick enough.

As he left Davis' cabin the Germans appeared in the little passageway aft, Davis in advance. He saw Jack the same moment the latter saw him and both raised their revolvers and fired. But neither had paused to take careful aim and both bullets went wide of their mark.

Edwards and the two other British sailors now sprang into the little passageway and levelled their revolvers at the foe. For a brief moment the Germans hesitated, and in that moment the British poured in a volley. Two men fell, another groaned, and two cursed—while at a shouted command from Davis, the fire was returned.

The sailor McDonald flung wide his arms and toppled to the floor.

"Back, sir!" cried Edwards. "They are too many for us."

The three retreated along the passageway until they reached the ladder leading to the bridge.

"You first, sir!" said Edwards, at the same time firing down the passage.

Jack hung back.

"After you," he replied.

"Don't be a fool now," said Edwards. "Hurry, while I hold them off."

Again he fired at the crowd of German faces down the passage, as did O'Brien.

Jack hesitated no longer and climbed the ladder rapidly.

"You next, O'Brien," said Edwards.

O'Brien sprang to the ladder, but a bullet from a German revolver halted him halfway. He toppled over without a word. Edwards glanced at him quickly once, saw that he was beyond help, and sprang to the ladder himself.

A bullet struck him in the side but it did not stop him. Jack, at the top, lent the man a helping hand, and a moment later Edwards stood beside him on the deck.

"No time to waste, sir," said the sailor. "Over the side with you, quick!"

Jack flung himself into the river as Davis showed his face on deck.



CHAPTER XXI.

AT SEA AGAIN.

Edwards, also about to leap overboard at that moment, paused, raised his revolver, took careful aim at Davis and fired. Davis uttered a hoarse cry, dropped his own weapon, and crumpled up on the deck. Edwards smiled grimly, dropped his revolver and leaped lightly into the water.

He came up a moment later beside Jack, who was treading water while he awaited him.

"Which way, sir?" asked Edwards. "You know where we are. I don't."

"This," said Jack, "is the Thames. We'll have no trouble making shore. Follow me."

Edwards did so and a few moments later both stood dripping on land.

"Now where to, sir?" asked Edwards.

"We'll have to hunt up Lord Hastings. He's gone to make his report to the British authorities. By inquiring a bit we should have no trouble finding him."

The lad was right. A subordinate officer directed them to the quarters of General Hamilton, where Jack felt sure he would find his commander. At the door of the general's quarters an orderly halted them.

"Is Lord Hastings here?" demanded Jack.

"He is closeted with the general," was the reply.

"Well," said Jack, "you tell him his first officer is here and wants to see him immediately."

The orderly hesitated, but a second look at Jack and he did as commanded. A moment later Lord Hastings dashed out, closely followed by Frank.

"What's wrong?" he demanded.

"Nothing, only that we have been chased off the submarine," replied Jack quietly. "Davis headed a conspiracy to capture the vessel and I was unable to act quickly enough. Edwards and I escaped."

"And O'Brien and McDonald?" inquired Lord Hastings.

"Dead!"

"How about Davis and the others? Weren't you able to account for any of them?"

"A few, sir," returned Jack briefly, "but Davis——"

"I think I got Davis, sir," Edwards interrupted quietly. "I took a shot at him just before I went over the side. He went down."

"I'm glad to hear that," returned Lord Hastings. "He is too dangerous a man to be at large. Besides, without him, the Germans will hardly get very far."

He turned to General Hamilton, who had followed him from his room, and added: "If you'll be so kind as to give me a detail of ten men, sir, I'll go and see about this matter. It may be that we can recapture the vessel."

General Hamilton acted quickly. He summoned an orderly and commanded that ten men be placed at Lord Hastings' disposal immediately. The men appeared on the run a moment later and Lord Hastings led them toward the river, where they all embarked in a small motorboat and headed for the spot where they had left the submarine.

But there was no submarine to be found. It had disappeared.

Lord Hastings uttered an exclamation of chagrin.

"They've gone," he said. "Edwards, I guess you didn't hurt Davis very bad. I don't suppose there was a sailor aboard who could navigate the vessel. Davis probably could."

"I'm sorry, sir," returned Edwards.

"So am I," returned his commander. "We'll have to catch that fellow, and it is likely to prove a hard job. However, the sooner we get after him the better."

"And what do you intend to do, sir?" asked Jack.

"We'll take another of these vessels and put to sea again," declared his commander. "We may come up with him sooner than we expect. But—we'll take a British crew this time."

It was now after daylight and Lord Hastings set about his preparations with vigor. Before evening the lads found themselves aboard one of the German submarines that had been captured and brought to the surface. The vessel was manned with a full complement of British underwater sailors. Edwards was among them.

"We'll go down the river immediately," said Lord Hastings, after a tour of inspection of the vessel, "and when we are at sea we'll fly the German flag. None of our submarines looks anything like this craft, so if we come up with the enemy we will be taken for a German. You may steam at ten knots, Mr. Templeton."

Jack gave the order and the vessel moved down the river.

Shortly after nightfall the submarine, U-6, was proceeding into the North Sea, for it was there that Lord Hastings believed he would be more likely to encounter Davis and the U-16.

"Besides," he explained, "our usefulness is not at an end in the matter of obtaining information from the Germans. We may put into Ostend again if necessary."

All during the night, although Frank, Jack or Lord Hastings was continually on the bridge, they did not encounter anything that looked like an enemy ship, although the U-6 dived several times when it drew close to a British ship of war—one of the blockading fleet Had the submarine approached too closely it would have drawn a shot from the battleship, whose commander could not possibly have known that the German submersible carried a British crew in the service of King George.

The following afternoon, having traveled far toward the east, they were to have an adventure.

Moving slowly along, and presenting the appearance, from a distance, of a little speck upon the surface of the sea, the U-6 continued toward the east. Frank had taken the bridge half an hour before and now was studying a faint smudge on the eastern horizon. A moment later and a second smudge appeared and then a third, to be followed almost immediately by a fourth.

"Strange!" he muttered. "Seems to be coming from the direction of Heligoland. Battleships all right, but the question is, British or German? Must be the latter, though how they figure to run the British blockade is more than I know. However, I haven't heard that any of our vessels are this close to Heligoland. It's too dangerous on account of the German mines."

He summoned Jack, who also gazed curiously at the smoke for some moments; but even while Jack gazed, the dim outline of a large battleship came into sight. Soon a second appeared and then a third.

"Must be German," said Jack. "Call Lord Hastings."

Frank did so and soon the commander of the U-6 appeared on deck.

Lord Hastings wasted no time in fixing the identity of the approaching vessels.

"Germans," he said briefly.

"Yes; but where are they going?" Jack wanted to know.

"Probably intend another raid on the British coast," returned Lord Hastings. "By the time they are in waters patrolled by our ships it will be dark, and they hope to pass them in the night. You haven't forgotten the raid on Scarborough and Hartlepool, have you?"

"No, I haven't," said Jack. "But I don't figure they would have the temerity to try another."

"They seem to have temerity enough to try anything," declared Frank. "However, I guess it's up to us to stop this raid."

"Right you are, Frank," said Lord Hastings quietly. "It's up to us."

"And how do you figure we are going to get all four of them?" demanded Jack.

"Well, with luck we might do it," replied his commander. "However, it would hardly be necessary for that. If we can sink two the others will turn and run."

"And shall we remain on the surface, sir?" asked Jack.

"No. We'll submerge until we are close to them. Then we can come up safely enough, for they'll believe us friends. We can sink one and get down again in time. Then, taking our calculations as to where they will be, we can come up again and have a try at another. We may as well submerge now."

Jack gave the order, and a few minutes later the U-6 was beneath the water, not even her periscope being allowed to show. Here she remained until Lord Hastings believed the German battleships had approached close enough to be in range of the submarine's torpedoes. Then she came to the surface again.

Lord Hastings had gauged the distance accurately. The German ships were now hard by and steaming swiftly forward. As the U-6 sprang up from beneath the water, there was some excitement aboard the German vessels, which soon quieted, however, as the Germans made out the lines of the vessel and caught the German flag with their glass.

"We're safe enough," declared Jack. "They take us for one of themselves."

"Much to their sorrow," said Frank.

"All ready below?" demanded Lord Hastings.

"All ready, sir," replied Jack.

"Good. Down with both of you then. I'll be down the moment the first torpedo has been fired, and we'll have to submerge as quickly as possible."

The lads obeyed Lord Hastings' command and took their positions.

"Ready with No. 1 torpedo," came Lord Hastings' command from above.

"Ready, sir," returned Jack, after a quick scrutiny.

"Ready with No. 3 torpedo," shouted Lord Hastings.

"Ready, sir," said Jack, and then exclaimed in an aside to Frank:

"By Jove! He's going to try and get two of them at once."

And such, indeed, was Lord Hastings' intention. The German battleships were so close together that Lord Hastings believed he could strike a double blow successfully and with perfect safety to his own vessel.

Signal flags now were displayed at the masthead of the foremost German battleship and Lord Hastings knew that some answer was expected from the submarine.

"Well, I can't decipher your signals," he muttered, "but I can give you some kind of a reply—which I don't suppose will be much to your liking."

He turned and gave a command to Jack; and Jack, in turn, flashed it upon the electric signal board below with the pressure of a button beneath his finger.

"Attention!" came the command now, displayed in letters of fire.

Then a brief lapse of time, in which all was silence below.

Then another signal showed red on the board.

"No. 1 torpedo! Fire!"

Again came that faint metallic click to which the boys had grown so accustomed, and a terrible engine of destruction sped over the water toward the German ships.

A moment later a second command flashed on the board.

"No. 3 torpedo! Fire!"

Once more the click and then nothing but silence. A moment later Lord Hastings hurried below.

"Submerge!" he ordered.



CHAPTER XXII.

TOWARD OSTEND AGAIN.

Jack had been ready for this command and repeated Lord Hastings' words immediately. Not a second was lost, and a moment later the tanks began to fill and the submarine sank lower and lower in the water.

Jack, who had glued his eye to the periscope, gazed at the German battleships as long as it stayed above water. In the few moments that it took the craft to submerge, he saw that two of the enemy's craft had been struck and that the other two had trained their big guns upon the U-6. His heart beat fast, for he was afraid the submarine would be unable to put a thick enough blanket of water above it to withstand the German shell, should the first shot be gauged accurately.

Just before the periscope disappeared beneath the surface, cutting off the lad's view, he heard the faint sound of a gun. He braced himself for the shock that he expected; but none came. The first shell had gone wide and he breathed easier. Before the second shot came, the U-6 was safe in the depths.

"Pretty close," the lad muttered aloud.

"What was pretty close?" demanded Frank, who had not heard the sound of the shot. "Didn't we hit either one of them?"

"Oh, yes, we got them both," replied Jack. "I was talking about our own escape. The Germans fired one shell at us and they can't have missed very far. Fortunately, we came down before a second."

"Shape your course due east, Mr. Templeton," commanded Lord Hastings at this juncture. "We'll have a try at another of them."

Jack gave the command.

"Twenty knots!" ordered Lord Hastings.

The U-6 leaped forward beneath the water like a thing alive. For fifteen minutes she sped on and then rose until her periscope showed above the surface.

"As I expected," said Lord Hastings. "The enemy is making for home, but we have outrun them and are now between them and their goal." He gauged the range carefully and then ordered: "No. 2 torpedo!"

Again all was expectancy aboard the submarine as all eagerly awaited the next command. It was not long coming.

"Attention!" the signal board read.

And a moment later came the next command:

"Fire!"

A shell sped across the water straight for the third German battleship. Through the periscope Lord Hastings saw the German vessel give a great lurch, then leap almost clear from the water, where it seemed to hang suspended for a full minute, before it came down again. As it did so there was a blinding flash and a detonation that was heard in the submarine.

"Pierced her magazine!" said Lord Hastings quietly.

He stepped aside that Jack might have a look above.

The latter's eyes sought out the spot just in time to see the giant battleship split in twain and disappear beneath the sea. Farther back he saw the two others of the enemy listing badly to port, and knew that they had received their death blow.

The fourth and last vessel was still unharmed and was bearing down on them at full speed. Even as Jack looked there came a puff of smoke from one of her forward turrets and a great splash, less than a hundred yards ahead of the U-6, told that the submarine had been discovered.

"Submerge!" cried Jack.

Lord Hastings repeated the command immediately for he realized that the vessel must be in danger. Even as the periscope disappeared from sight, there was a second flash from the German and a shell glanced off the bow, sending the U-6 staggering and hurling the officers and crew to the floor.

The men picked themselves up quickly and all stood silent for a moment.

"Test the pumps quick!" was Lord Hastings' first command after he had regained his feet.

"No damage there, sir," came the cheering news a moment later.

"Signal the engine room! Something may have given way," ordered Lord Hastings.

This was done, but the engineer reported no damage.

Frank and Jack both breathed easier, as did Lord Hastings.

"A pretty narrow squeak," remarked Lord Hastings calmly.

"Rather, sir," agreed Jack dryly. "And now shall we go after the other one, sir?"

"I guess not," replied his commander. "After this day's work we can afford to let one escape. There is no use taking further chances. Besides, she'll be on the lookout for us and might cripple us the moment we showed ourselves. No; we'll head west again and won't come to the surface until we are well out of this. You may come about, Mr. Templeton, and proceed due west at ten knots."

This was done and the U-6 did not come to the surface again until her commander felt sure that he had no longer need to fear the single remaining German battleship. Then, upon the surface again, Lord Hastings, Frank and Jack ascended the bridge.

Through their glasses, far back, they could still see the German battleships, which, though wounded unto death, were still afloat, apparently battling desperately to resist the sea that was trying to draw them under. The water was still full of bobbing heads—the German sailors who had leaped into the sea.

"Poor fellows," said Lord Hastings compassionately.

"Why didn't the other ship stop and pick them up?" demanded Jack.

"Didn't have time, I guess," returned Jack dryly. "Her commander was in too big a hurry to get away from there. He deserves the same fate for running away from them, if you ask me."

"He certainly does," agreed Lord Hastings. "However, there is nothing we can do for the poor sailors in the water; we have no room for them here. They will have to shift for themselves. It's the fortune of war."

"And now where to, sir?" asked Frank.

Lord Hastings looked at him amusedly.

"I guess that is the hundredth time you have asked me that question," he said. "However, I don't mind answering it, although you will find some day, should you chance to serve under another commander, that such questions are not received with very good grace. I believe we shall take another little run into Ostend."

"Good, sir!" said Jack. "We did very well on our last trip. Perhaps we shall be fortunate enough to learn something this time."

"Who knows?" said Frank, with a shrug of his shoulders. "However, the nearer the enemy we are, the more chance for action. The sooner we get started the better I shall be pleased."

"It's a short run from here," said Lord Hastings, "and I believe we shall be safe enough if we make the attempt in broad daylight. We'll take a chance."

He gave the command to go forward and the U-6 moved swiftly ahead.

As Lord Hastings had said, it was not a long run, and two hours later, standing on the bridge, the boys made out in the distance the lofty spires and steeples that they felt sure was the Belgian seaport. And they were right.

The U-6 was not molested, not even challenged, as she moved slowly into port, flying the German flag, her officers and crew all attired in German uniforms.

"Where are all the big German battleships?" asked Frank in surprise, after sweeping his eye over the water in all directions in a vain effort to locate one of them.

Jack smiled.

"You ought to know there are no German battleships here," he said.

"But——" began Frank.

"The battleships are still safely bottled up in Heligoland," Jack explained. "While Ostend is called a German naval base, it is, strictly speaking, nothing but a submarine base. The under-sea boats have been able to run in here without much difficulty, but the larger vessels could hardly get by on the surface."

"I see," replied Frank. "I hadn't thought of that."

"But it seems to me we are getting in pretty easily," said Jack. "It's a wonder we are not challenged. I'm always suspicious of anything that is attained too easily. I wonder if we can be suspected?"

"Not likely," remarked Lord Hastings. "We've come pretty straight, in spite of our short stop. They could hardly have had word of the sinking of their vessels in the Thames as yet."

"Unless from Davis and his crew, sir," suggested Frank.

"I don't believe they have learned anything from Davis," Jack declared. "That bunch of vagabonds are probably prowling about seeking whom they may devour."

"And I have a faint hope that they may seek to devour us before long," said Frank with a smile.

"I've sort-o had that wish myself," Jack seconded his chum. "However, I feel certain that we shall come upon them sooner or later."

"And still," said Lord Hastings, "there really is no telling where they are likely to be. They can't wander too far from their base. They'll have to put in some place every so often, you know."

"They will live off their victims, providing they have any," said Frank. "To find them is like looking for a needle in a haystack. We might have to search the seven seas."

"And then not find them," Jack added.

"Well, if we do come up with them, I'd like to lay my hands on Davis," declared Frank.

Jack smiled.

"You laid hands on him last time, if I remember rightly," he said. "Also he laid hands on you, and a deal more roughly, too. He might not let you off so easily again."

"Think so, do you," said Frank, a little sulkily. "He was just lucky, that's all."

"It may have been a little luck," Jack admitted. "At the same time, you will have to give the fellow credit. He can use his hands. I guess if we encounter him again it will be up to me to handle him."

"You don't seem to have much confidence in yourself," remarked Frank sarcastically.

"Well, a fellow has to have confidence in this world," was his chum's reply. "It may be that he would be too much for me, too; but I've an idea I could take care of him."

"Well, you won't. He's my meat next time," declared Frank.

"We won't argue about it," smiled Jack. "We'll let events shape themselves when the time comes. Only, if he falls to my lot, I'll try to even up your score, too."

"And if he comes to me," grinned Frank, "I'll put in a few blows for you, seeing that you are so obliging."



CHAPTER XXIII.

AN UNEXPECTED ENCOUNTER.

"Now that we have so kindly been permitted to enter," said Lord Hastings, "I don't believe it would be half a bad idea for us to go ashore; or at least two of us."

"I speak to go with you, sir," exclaimed Frank.

"So do I, sir," said Jack.

"Well, all three of us can't go," Lord Hastings decided. "We'll draw straws to see who are the fortunate—or unfortunate—two. I'll draw with you. The one who gets the short one loses."

He drew three toothpicks from his pocket, and putting them behind his back, broke one. Then he held them out to Frank.

"Pick one," he said.

Frank did so, and glanced at it eagerly. It had not been broken.

"I go," he declared.

"It's between us now," said Lord Hastings to Jack. "Pick one, Jack."

He held up the remaining two toothpicks Jack gazed at them earnestly.

"I'll take this one," the lad said at length, and picked the one on the right.

"You win," said Lord Hastings quietly. "I'm the fellow that must remain behind."

Jack was equally as pleased as Frank, but he did not manifest the same enthusiasm.

"And what is it you expect us to learn, sir?" asked Jack. "I'm sure I haven't any idea."

"Nor I, sir," declared Frank.

Lord Hastings smiled.

"You see," he said, "it might have been better to let me go." Then he added after a brief pause: "I don't know that I had any particular plan in view. I was just going ashore and stroll about a bit. It is barely possible that one of you may overhear something. I wouldn't stay more than two hours at the most." He glanced at his watch. "Two o'clock now," he said. "I shall expect you back here at 4.30 at the latest."

The lads nodded.

"Will it be best for us to row ashore ourselves, sir?" asked Frank. "Or shall we have one of the men take us?"

"You would better go alone," replied Lord Hastings, after a moment's hesitation. "You can tie your boat up some place. I hardly think any one will bother it. A sailor might betray all of us unconsciously. In a game like this, the fewer the better is my motto."

"Come on, Jack; let's be moving," said Frank impatiently. "There is no use staying here all day. Hurry up."

"Now you just hold your horses," replied his chum. "We'll get there soon enough—maybe a little too soon, so far as we know."

Nevertheless the lads wasted no further time in talk and five minutes later the two were rowing shoreward in a little boat.

As they rowed along, they saw several other under-the-sea craft at anchor and upon the bridges of one or two stood officers. These saluted as the boys passed, but none so much as hailed them.

"These German uniforms seem to be pretty good things," Frank remarked in a low voice. "Guess they carry the entree any place in the town."

"We'll see," returned Jack briefly.

Fifteen minutes later they reached a landing and climbed ashore. Then they tied the little boat up, against their return, and started down the first street.

"Pretty likely looking town, this," declared Jack, as his gaze roved about.

"Yes," Frank agreed, "but you can still see the marks of the German shells that struck during the siege."

They looked around with interest—though not so curiously as to attract attention—and continued along the street.

For an hour and more they strolled about gazing at the various sights of interest, but learning nothing of value. Several times they approached knots of German officers, attempting to overhear their conversation. But there was nothing in any of this street-corner talk which was worth hearing, being concerned chiefly with accounts of adventures and curious episodes.

The lads were saluted frequently as they passed along and they returned these salutes with customary German stiffness. No one spoke to them and for this they were duly thankful, although each spoke German like a native and ran little risk of detection on that score.

Frank glanced at his watch.

"Five minutes to four," he said. "Time to be moving back."

Jack nodded.

"May as well, I guess," he agreed. "If you ask me, this has been an afternoon wasted. I don't seem to have learned anything of importance and I don't believe you have either."

"You've been with me right along," replied Frank. "You know as much as I do."

They retraced their steps toward the water front.

And here, in the place they would have felt least likely to encounter a familiar face, that very thing happened. They were still a short distance from the water-front when a man brushed by them closely, walking rapidly. His head was lowered and his face was well muffled in spite of the fact that the day was not cold. There was something familiar about him, though neither lad could place him. After he had passed both lads turned and looked after him with one accord.

"There is something familiar about that fellow," Jack declared. "I've seen him some place before."

"And so have I," agreed Frank. "And I have a feeling that it was not under very favorable circumstances."

Each lad racked his brain for a brief moment; then Jack said:

"Well, I guess it doesn't make any difference. Let's go."

He turned about and took a step forward. Frank was about to do the same, when a sudden thought flashed into his head.

"Wait a minute," he called. "I think I've got him."

"Who?" demanded Jack.

"Davis!" said Frank quietly. I'll bet a pretty red apple that man is Davis."

"By Jove!" said Jack. "I wonder—now what would he be doing here?"

"I don't know," replied Frank, "but I feel sure that's who it is. Come on. Let's go after him. We'll lose him in a minute."

Even as he spoke the man he felt sure was Davis turned a corner. Not waiting for Jack to agree, Frank hurried after him. Jack followed.

The man ahead was walking rapidly, but the two lads gained on him. After two blocks' walking they were less than fifty yards in the rear—slouching along cautiously, with heads lowered, for they did not wish to be recognized if the man were really Davis.

Once the man turned and gazed at the two figures behind him; then, apparently satisfied that he was not being followed, he moved on again.

After two more blocks he doubled around a corner. Frank and Jack turned the corner a moment later, just in time to see Davis mount a short flight of steps, open a door and enter the house.

Frank and Jack walked by, taking careful note of the number of the house, however, and without glancing up again, continued down the street and turned the next corner.

There they halted as of one mind while Frank peeped around the corner, remarking:

"Don't want him to trick us. I don't think he knew he was being followed, but you never can tell."

The lads stood there for perhaps ten minutes; then Jack reached a decision.

"As long as we have come this far," he said, "we may as well finish this man hunt. We'll go and have a look for him."

"How do you figure we are going to get into the house?" demanded Frank. "Or do you just plan to ring the bell and ask for 'Mr. Davis'?"

"We'll have to get in some way," returned Jack, "or else admit that we are wrong."

"I won't admit I'm wrong," declared Frank grimly. "I feel positive the man is Davis."

"So do I," replied Jack; "else I wouldn't be so keen about getting into that house. We'll go back and skirmish around a bit, anyhow."

They retraced their steps slowly, and passing the house where the man had entered, took careful note of it.

It was a two-story building. Steps led to a porch, not high above the street, but still high enough to make the single window in front beyond reach from the street below. A narrow passage was between it and the house on the left. It was built flush against the house on the right.

At the corner the lads again turned and retraced their steps. "I'm going to try the door," said Jack. "You slink back in that dark alleyway until you hear from me."

Frank signified that he understood, and passing the house, did as Jack had instructed, the latter mounting the steps quietly and swiftly.

The lad laid a hand on the knob and turned it. Then he pushed on the door, but it held fast.

"Locked," he said, plainly disappointed.

There was no window in the little vestibule and the single front window was beyond reach from the porch. Neither was there a transom that could be forced.

"No means of getting in here," Jack told himself.

He descended the steps and joined Frank in the alleyway.

"Well?" Frank greeted him.

Jack shook his head.

"Can't get in that way," he said.

"Well," said Frank, "I have been doing a little exploring while you were up there and I have found a way."

"How?" asked Jack, a little surprised.

For answer, Frank motioned to a little aperture in the side of the house, close to the ground.

"Window into the basement," he explained. "It's open."

Jack wasted no time. He dropped to his hands and knees and, pushing the window open, shoved his feet through. Then he wriggled his body through the opening and dropped.

It was not a hard fall and he picked himself up unhurt. He called softly to Frank and the latter was beside him a moment later. Walking softly, Jack led the way up a little flight of stairs to a door which opened easily. He stepped inside.

Frank followed and Jack closed the door. It was perfectly dark.

But suddenly the darkness was lighted up. The astonished lads gazed into the muzzles of a pair of automatics and a well-known voice cried:

"Hands up!"



CHAPTER XXIV.

ANOTHER UNPLEASANT SURPRISE.

To say that the lads were astonished is putting it mildly. There they were, so they believed, sneaking upon an unsuspecting victim and now they found themselves absolutely in that victim's power, for it took but the first glance to assure them that the face that gazed so evilly and sardonically into theirs was the face of Davis.

Now Davis grinned at them.

"I was expecting you, gentlemen," he said with biting sarcasm. "I did not wish to seem discourteous, which is the reason I welcome you in person. But, also, knowing your kind, I surmised that you would not announce yourselves at the front door, as would most British gentlemen; therefore I receive you here. I assure you you are most welcome."

All this time he kept each lad covered with an ugly-looking automatic.

As neither Frank nor Jack replied, Davis continued.

"I would just like to add that if you desire to get ahead of me it will be necessary to arise very early in the morning. What kind of a spy do you think I am, anyway, not to know when I am being followed? I assure you, gentlemen, you have misjudged me. I was not born yesterday."

Still neither lad replied.

"And now," Davis went on, "I must ask you to be so kind as to precede me to the parlor, where I shall entertain you more comfortably."

He emphasized this statement with a slight gesture with one of his revolvers and there was naught for the lads to do but obey.

Davis followed them closely, still covering them with his two revolvers. In the parlor he motioned them to seats and took a chair across the room.

"Now," he said, "I would be pleased to have you tell me how you escaped from our enemies, the British."

"Well, I can see no harm in enlightening you," said Jack. "I would have supposed that, being so brilliant, you had guessed it by this time. We are British officers and not German."

"Would it surprise you," queried Davis, "if I should tell you I had surmised as much? And our good friend, Commander Bernstorff"—and here Davis laughed—"how is he?"

"Well," replied Jack calmly. "And now I wonder if you would explain a few things to me?"

"You are at liberty to ask," smiled Davis.

"Then, how did you get here—why did you venture here—and what of your little private expedition?"

"Those," said Davis, "are what I should call considerable questions. However, I can see no harm in answering them, particularly as you will never be able to repeat what you hear now. I came here in our submarine the U-16, which, by the way, I have rechristened The Vulture—a suitable name, don't you think?—and I came here because I had business here. Now, as to your other question. Our little privateering expedition is progressing famously. We have already sunk one British ship and secured a quantity of booty, which may have something to do with my presence in Ostend."

"I see," said Jack.

"And," continued Davis boastingly, "I came in right under the noses of the Germans. My submarine lies in the harbor at this moment. I came ashore in the guise of a German officer. I was not questioned, nor were you, I take it?"

His last words formed a question, and Frank answered.

"No, we were not questioned," he said.

"I thought not. Well, when I presently have finished my business—which, by the way, has been increased since your arrival—I shall make my way back to my vessel and put to sea again. I shall bother none of the Germans nor any ships of war unless they bother me—my business is with ships of commerce, where there is booty to be had—and when I have reaped enough I shall go to America, where I shall live the life a gentleman should."

"You'll make a fine gentleman," said Jack sarcastically.

"You think so?" said Davis, apparently unruffled. "So do I. But time presses. I am sorry I can entertain you no longer. You will please precede me from this room and upstairs."

He arose, and with one revolver, motioned the lads out the door. There was nothing for it but to comply; for both lads realized that while they might have jumped Davis, one of them probably would be shot down; nor was it for his own sake that each hesitated.

They preceded Davis up the stairs and into a large unfurnished room. As he entered, Jack looked toward the window. It was heavily barred and the walls of the room, he saw, were very thick. Once locked in that room, the lad realized, there was little hope of escape.

"Now," said Davis, "please cross the room and stand with your backs to me. I shall leave you here to amuse yourselves. You will have lots of time, for, I venture to say, the room will not be entered for months to come—not until I return, which may not be for months. Then I shall give myself the pleasure of calling on you. Now, good-bye. Turn and face the wall, please."

Jack realized that it was now or never and he took a sudden decision.

"Face the wall, Frank," he commanded quietly. "It's no use."

Frank obeyed.

"You too, if you please," said Davis blandly, flourishing a revolver, while at the same time he returned the other to his pocket.

"Look here, Davis," said Jack quietly, "this thing has gone far enough. We have been highly amused with your entertainment, but now it is time to call a halt."

Davis looked at him expectantly.

"Well?" he queried.

"Just this," said Jack calmly. "Unless you drop that revolver this minute, I shall have to take it away from you."

He gazed at Davis steadily.

The latter's shifty eyes could not meet the steady gaze of the lad and he looked away, but kept Jack covered with his revolver.

"Oh, I guess not," he said.

"Oh, yes I shall," said Jack easily.

"Come," said Davis, pulling himself together and raising his revolver so it pointed between Jack's eyes. "Enough of this. Get back there now or I shall fire."

Instead, Jack took a step forward, still looking Davis squarely in the eyes.

"Put down that gun!" he commanded sharply.

His tone startled Davis, and for a brief moment he allowed the weapon to waver; and in that moment Jack leaped upon him.

Taken off his guard, Davis nevertheless still had time to raise the revolver and fire. Jack staggered back as he felt something like a red-hot iron pierce his right arm; and the member dropped limply to his side.

Again Davis fired, but Jack ducked even as he pulled the trigger and the bullet passed over his head.

There was a cry from behind him and Frank pitched forward to the floor. The bullet had struck him a glancing blow on the side of the head.

Jack's heart grew sick as he heard his chum's cry, for he realized in a flash what had happened; but he did not turn his head to look. Instead, stooping low, he leaped lightly forward and seized Davis' pistol arm even as the man fired again. Jack jerked the arm upward at the moment the weapon went off and the bullet passed him harmlessly. Then, with a vigorous wrench, the lad twisted the revolver from Davis' hand and kicked it to one side as it fell to the floor at his feet. Then he struck Davis sharply across the face with his left hand, and as the man staggered back, thrust his hand into the pocket where so recently Davis had placed his second revolver.

Davis grabbed at it but too late.

Jack stepped back and, walking across the room, picked up the other weapon. Then, opening the door, he tossed both weapons outside, closed the door and faced Davis.

"I've still got a couple of guns in my own pockets," he said quietly, "but I'm going to thrash you within an inch of your life without use of a weapon—and with a bad arm besides. I may shoot you later, I haven't decided about that yet. It all depends upon how badly you have hurt my friend here."

He stepped forward and aimed a hard blow at Davis with his left fist. Davis stepped aside and the blow missed. At the same time Davis swung hard with right and left and the second blow caught Jack on the helpless right arm. Jack winced but said nothing. He was deadly cool, and he advanced upon Davis smiling.

"Now," he said, "I'll give you an imitation of how I treat a dog like you."

He backed Davis into a corner of the room by a series of single-arm feints and then struck out heavily. Davis put up both arms to block the blow but it did him no good. His guard was swept away as though it had been a feather and the heavy blow crashed through and caught him in the face.

Davis staggered back with arms covering his face protectingly and again Jack struck him heavily between the eyes. Davis fell to the floor in a heap, where he lay whining. Jack stood over him angrily.

"Get up!" he commanded quietly. "Get up and fight. I'm not through with you yet."

Davis grovelled upon the floor, seeking to clasp the lad's knees.

"Get up!" commanded Jack again.

Davis made no move to rise.

Jack stretched out his uninjured arm and jerked the man rudely to his feet.

"Put up your hands and fight," he ordered. "Don't show yourself the dog you are!"

Davis did as Jack commanded and aimed a blow at the lad's head.

Jack promptly knocked him down again.

A second and a third time this was repeated; but after the last fall Davis grovelled and moaned like a whipped child.

Jack gazed down at him in disgust.

"And I hadn't half begun," he said angrily. "However, I can't stand here and knock down a man who will make no attempt to defend himself. I am through with you now. You can go."

Slowly Davis raised himself to his feet and moved toward the door, looking furtively about as he did so. As he reached the door, he sprang suddenly outside with a loud cry. Jack sprang after him and seized his arm just in time to deflect a bullet he would have fired from a revolver he picked up without.

"I thought so," said Jack grimly. "I thought that was about your size. I had it all figured out, only when it came to a show down I couldn't do what I had intended. I had intended to let you pick up your gun, and when you tried to shoot me, to kill you. But I can't do it. Get out of here now before I change my mind."

Davis started to move along the hall, but at that moment there were heavy footsteps upon the stairs and a moment later a figure in the full uniform of a German battleship commander stood before them.

"What's the meaning of this?" he demanded in a harsh voice.

He glanced at the two quickly, and then realizing that he apparently was talking to a German naval officer, and his subordinate, he addressed Jack.

"You know his Imperial Majesty's orders in regard to fighting with civilians?" he asked.

Jack could do nothing but bow.

"Then," said the commander, "I shall have to place you under arrest!"



CHAPTER XXV.

DOOMED TO DIE.

It was a bitter disappointment to Jack, but he felt he could do nothing but submit. True, he thought to himself, he could probably have attacked the German commander, and perhaps have overcome him; but there was Frank to be considered, and his own injured right arm. No, he felt he could do nothing but submit.

"Very well, sir," he answered the German, "but first you will please permit me to see to my friend."

He indicated Frank's prostrate form across the room. The German saw it then for the first time and nodded assent.

"Also," said Jack, "it would be well if you did not permit that man," indicating Davis, "to escape. He is a traitor."

"So?" exclaimed the officer.

He drew his revolver and mounted guard over Davis.

"There is really no use my guarding you," he said. "Half a dozen of my men are below, so you could hardly escape."

In the meantime Jack bent over Frank and raised his chum's head to his knee. Then he arose, asked permission of the German to leave the room for water. The permission was granted and Jack returned a moment later, his cap filled with water.

He sprinkled the water over Frank's face and soon perceived signs of returning consciousness. Frank drew a deep breath and opened his eyes. Then he pushed Jack aside and sat up.

"What's happened?" he asked in a faint voice.

In a few words Jack explained.

"I remember now," said Frank. "Help me up."

Jack did so and then for the first time Frank caught sight of the German naval commander.

"What's he doing here?" he asked of Jack.

"Oh, he's just arrested us; that's all," said Jack.

"Yes," said the German, "and I must ask you to accompany me now. You shall come aboard my ship until this matter has been investigated thoroughly. I'll take charge of you, rather than to turn you over to the military authorities; for after all you are naval officers and I shall help you if I can. Please precede me; and you too," this last to Davis in a gruffer tone.

All proceeded below, where eight or ten other men stood waiting. Then all marched away.

Reaching the water front all entered a small boat and were rowed toward a submarine, perhaps a quarter of a mile away.

As they passed, Jack noticed the U-6 a short distance away and made out Lord Hastings' figure on the bridge. He raised an arm and waved it. He was not sure that his signal had been seen, but he did not wish to draw further attention to his commander.

Aboard the submarine the German commander had them taken to his own cabin, where he insisted upon his own surgeon dressing Frank's wound and having a look at Jack's arm.

The surgeon pronounced both injuries slight and prescribed rest. Several times Frank caught the German commander looking at him curiously and it worried him somewhat, for there was something familiar about the man, though Frank could not seem to place him.

"I'm just trying to think," said the German to Frank, "where I have seen you before. I don't place your name."

"I can't remember you, sir," replied Frank.

Suddenly the German slapped his thigh. Frank's heart sank for some reason he was unable to explain to himself.

"I have it!" exclaimed the German. "You are the lad whom I captured from a British submarine in the Kiel Canal not so long ago. I remember you well now. You escaped. So you are a British spy, eh?"

"I—I——" began Frank.

The German raised a hand.

"It will do you no good to deny it," he said quietly. "I cannot be mistaken. Besides, I can plainly see now that you are no German; and this supposed-to-be German officer with you is also British. I can see it now. So is the other prisoner, though I cannot see what you should have been fighting about."

Neither Frank nor Jack replied. Each realized that there was no use in entering a denial.

"I'll take my oath I'm sorry for this," said the German. "Of course, you know there is but one thing I can do?"

Frank nodded understandingly.

"You were found within our lines in German uniforms," said the commander. "Therefore you are spies and must be treated as such. I myself shall call a court martial within the hour. You must be shot. The other man will be tried separately, but I have no doubt he will suffer the same fate. Orderly!"

A second officer entered the room.

"Have these prisoners closely guarded and bring them here an hour from now," he ordered. "Then summon the commanders of the other vessels in the harbor. They shall sit on a court martial here. Hurry."

Jack and Frank were led from the cabin and locked in another compartment at the far end of the ship where they sat in silence until they were conducted to the commander's cabin.

And as they gazed about the cabin the eyes of both opened wide in surprise, though they made no sound.

For there, sitting with five other German officers about the table, was none other than Lord Hastings, still wearing his German uniform. He was sitting on the trial board.

The German commander who had captured them presided.

"Bring in the other prisoner," he commanded.

A moment later Davis was led in. The lads saw a surprised expression flash over Lord Hastings' face as his eyes rested on Davis; but he sat still.

Then, suddenly appearing to take a close look at Frank and Jack for the first time, he jumped to his feet and approached them. After a careful scrutiny, he uttered a loud exclamation and turned to the other officers.

"Sirs," he said quietly, "you have indeed made an important capture. These men, although apparently young, are two of the most trusted of British spies. I know them, for I have come in close contact with them," and he glared at them angrily. "So, we have you at last, eh?" addressing the boys, who shrank back in well-feigned alarm.

As for Davis, he said nothing. He had been doing a lot of thinking and had come to the conclusion that it was better to postpone his fate by being rescued with Frank and Jack, if possible; for he had a pretty shrewd idea that Lord Hastings was there for some such purpose.

"So," continued Lord Hastings, eyeing the two lads angrily. "I have you, eh. I would like to put a hole through each of you myself." He half drew a revolver.

The German commander interfered.

"None of that, if you please, sir," he commanded sharply. "They shall have trial; and if they are convicted, as I have no doubt they will be, I shall bestow upon you the doubtful honor of performing the execution."

"And I shall be pleased indeed, sir," replied Lord Hastings with a leer.

The German commander turned from him in disgust.

"It is such men as you, who are a disgrace to the navy," he said quietly.

"Sir!" exclaimed Lord Hastings, facing the German in apparent wrath, though nothing could have pleased him better—things were working out much better than he had dared hope.

"Tut! Tut!" exclaimed the German commander. "I have no time to quarrel with you now. But when the war is over, it will give me much pleasure to put an end to one of your ilk."

"I shall remember that!" exclaimed Lord Hastings. "You shall answer to me, sir."

"When the war is over, I shall be very much at your service," was the quiet rejoinder. "But now to business. Prisoners, you may all stand up together. Your name?" he demanded of Jack.

"Templeton, sir," replied the lad quietly.

"And yours, sir?" demanded the German of Frank.

"Chadwick, sir."

The German turned to Davis.

"Davis, sir," replied the man before the German could propound the question.

"Have any of you prisoners anything to say in extenuation of your actions?"

There was no reply.

"No reason why the death sentence should not be passed upon you?" continued the German.

Still there was no reply.

The German commander then explained what he knew of the three and called for a vote.

"Commander Derndorff?"

"Death!" was the response.

"Commander Hellwig?"

"Death!"

"Commander Berne?"

"Death!"

"Commander Blough?"

"Death!"

"Commander Bernstorff?"

Lord Hastings' response was louder than the rest and he smiled evilly as he cried:

"Death!"

The German commander who had captured the lads made a grimace but said nothing.

He paused a moment and then declared quietly:

"My verdict also is death!"

Lord Hastings, apparently, could restrain his impatience no longer.

"Good! Good!" he cried.

"The sentence of this court martial," continued the German commander unheeding Lord Hastings, "is that the prisoners all be shot at sunrise tomorrow. Commander Bernstorff, since you are so eager to perform the disagreeable duty, you may command the execution; and that your men may think the less of you, as president of this court martial, I order you to choose the firing squad from among your own crew."

Lord Hastings beamed on him.

"It shall be done with pleasure," he declared eagerly.

"And," continued the president of the court martial, "you shall take the prisoners aboard your own vessel and you shall be held responsible for them. I could almost hope they would escape, so that you should suffer," he added to himself.

"Good, sir. Good!" cried Lord Hastings. "I shall remove them at once, sir."

"One thing more," said the commander sharply. "They must not be ill-treated. Understand?"

Lord Hastings' face fell in well-feigned disappointment. He appeared to draw himself together, saluted and said with an apparent effort.

"You shall be obeyed, sir."

"Take them away, then."

Lord Hastings ordered the three marched to the side of the vessel, where they stepped aboard the little boat. Then they were rowed rapidly toward the U-6.

As they neared the submarine, where they knew lay safety, the spirits of the lads soared once more, in spite of their wounds. Frank expressed Jack's sentiments as well as his own when he leaned close to Lord Hastings and muttered:

"Close shave, sir!"



CHAPTER XXVI.

MORE TROUBLE.

"You can believe me or not, but it feels pretty good to be back here."

The speaker was Frank as he stood upon the bridge of the U-6.

"It does, indeed," returned Jack, who stood by his side. "To tell the truth, I was afraid we would never get away. I thought we were goners, sure. And see who we have with us, our old friend Davis."

For Davis at that moment came aboard from the small boat beside the submarine. He grinned at the two boys feebly.

"Well, I'm glad to be back along with you," he said.

"I don't imagine you'll be glad to be back very long," said Jack dryly. "It seems to me you might as well have stayed where you were. The result probably will be the same. Only this time you'll have to face a British court martial and they'll probably hang you."

"While there's life there's hope," Davis spoke sententiously. "Which is the reason I didn't say anything over there."

He waved his hand in the general direction of the German submarine they had so recently left.

"Well, I'm much obliged, I'm sure," said Frank. "If you had spoken when you recognized Lord Hastings, it would have been all off with all of us. However, I'm afraid I shall be unable to speak a word in your behalf."

Davis shrugged his shoulders and turned away as Lord Hastings approached.

"Below with you all, quick!" exclaimed the latter. "Don't you realize you are prisoners? What do you suppose some of these German officers would say if they saw you making so free of this vessel, eh? They'd probably come over to see what is wrong. Get below!"

Lord Hastings spoke gruffly, for he had risked much to assure their safety and he did not wish his plans to go for naught. Frank, Jack and Davis obeyed without a word.

"Now," said Lord Hastings when all were safely below, "we'll have to get away from here."

"There should be no trouble about that," said Frank. "All we have to do is submerge and move off."

"And I suppose these other fellows will remain idle and watch us go," exclaimed Lord Hastings sarcastically. "Don't you believe it. We are likely to have trouble. They'll probably have a shot or two at us and we'll be fortunate if one doesn't strike home. Besides which, if we do get down safely, they'll probably chase us."

"Well, they can't find us under the water," Frank stated.

"Perhaps not," agreed Lord Hastings, "but we'll have to come up some time and when we do they are likely to be waiting for us. However, there is no use hesitating now. Every minute makes our situation more precarious. You may submerge to five fathoms, Mr. Templeton."

Quickly Jack gave the command. Immediately the bridge wound into the little conning tower, which at once closed, and the submarine began to sink gradually.

Lord Hastings glued an eye to the periscope and watched developments above.

"Just as I feared," he exclaimed. "They have seen through our ruse. There is excitement aboard all the enemy. Twenty knots, Mr. Templeton, and shape your course due north."

The little craft leaped ahead as Jack gave the command; and at the same moment a torpedo, fired by the nearest enemy craft, flashed through the water where the U-6 had been a moment before. It was a narrow escape.

A second torpedo flashed above the submarine just as it finally disappeared beneath the water; and a third did likewise.

Lord Hastings drew a breath of relief as he moved from the periscope—he could see no longer, the water having passed over the "eye" of the submarine.

"We're safe enough for the time being, at any rate," he declared. "Keep to your course, Mr. Templeton, until I give the command to alter it."

Jack saluted.

"Very well, sir," he said.

"And now," said Lord Hastings, gazing about, "the question remains as to what is to be done with Davis. Where is he?"

Frank looked about hurriedly.

"He was here a moment ago, sir," he replied. "He was right behind me."

"Well, he's not here now," said Lord Hastings. "There is no doubt about that. However, he can't have gone very far. We'll have a look for him."

Frank followed his commander aft.

They peered into every compartment in that end of the vessel. They searched the engine room and all other sections; but there was no sign of Davis; Lord Hastings scratched his chin in perplexity.

"Now what do you think of that?" he said slowly. "But he was on this vessel and he can't have got off. Therefore he must be here."

"There is one place we haven't looked, sir," said Frank.

"Where?" demanded Lord Hastings.

"Your cabin, sir."

"He would hardly have sought refuge there," said Lord Hastings.

"There is no telling, sir," replied Frank. "We may as well have a look."

"Yes, we may as well have a look," repeated Lord Hastings.

He led the way forward again and pulled up before the door of his cabin, which was closed.

"Now I could have sworn I left this door open," said Lord Hastings.

He laid a hand on the knob and turned it; but the door would not open.

"Hm-m-m," muttered Lord Hastings. "Somebody is in there all right. Guess it must be our friend Davis." He raised his voice and called: "Davis."