reply.

"Thank you for your good work. Best of luck."

From the S.N.O. (senior naval officer) came another message. Frank picked it up.

"Set course 188 degrees. Keep lookout for inbound transports to be convoyed. Ten ships."

Again the destroyer swung into line. It was almost seven o'clock—after dark—when the lookout aboard the Plymouth reported:

"Smoke ahead!"

Instantly all was activity aboard the destroyers. Directly, through his glass, Jack sighted nine rusty, English tramp steamers, of perhaps eight thousand tons, and a big liner auxiliary flying the Royal Navy ensign.

Under the protection of the destroyers, the ships made for an English port. The night passed quietly. With the coming of morning, the flotilla was divided. The Plymouth stood by to protect the big liner, while the other three destroyers and the tramp steamers moved away toward the east.

"This destroyer game is no better than driving a taxi," Frank protested to Jack on the bridge that afternoon. You never see anything. I'd like to get ashore for a change. I've steamed sixty thousand miles since last May and what have I seen? Three ports, besides six days' leave in London."

"You had plenty of time ashore before that," replied Jack.

"Maybe I did. But I'd like to have some more. Besides, this isn't very exciting business."

Night fell again, and still nothing had happened to break the quiet monotony of the trip. Lights of trawlers flashed up ahead. Interest on the bridge picked up.

"Object off the port bow," called the lookout.

"Looks like a periscope," reported the quartermaster.

Frank snapped his binoculars on a bobbing black spar.

"Buoy and fishnet," he decided after a quick scrutiny.

Frank kept the late watch that night. At 4 a.m. he turned in. At five he climbed hastily from his bunk at the jingle of general alarm, and reached the bridge on the run in time to see the exchange of recognition signals with a British man-o'-war, which vessel had run into a submarine while the latter was on the surface in a fog. The warship had just rammed the U-boat.

"Can we help you?" Frank called across the water.

"Thanks. Drop a few depth charges," was the reply.

This was done, but nothing came of it Frank returned to his bunk.

"Pretty slow life, this, if you ask me," he told himself.

He went back to sleep.

CHAPTER II

THE BOY CAPTAIN AND HIS LIEUTENANT

The U.S.S. Plymouth was Jack Templeton's first command. He had been elevated to the rank of captain only a few weeks before. Naturally he was not a little proud of his vessel. When Jack was given his ship, it was only natural, too, that Frank Chadwick, who had been his associate and chum through all the days of the great war, should become Jack's first officer.

In spite of the fact that Jack's rating as captain was in the British navy, he was at this moment in command of an American vessel. This came about through a queer combination of circumstances.

The American commander of the Plymouth had been taken suddenly ill. At almost the same time the Plymouth had been ordered to proceed from Dover to Liverpool to join other American vessels. Almost on the eve of departure, the first officer also was taken ill. It was to him the command naturally would have fallen in the captain's absence. The second officer was on leave of absence. Thus, without a skipper, the Plymouth could not have sailed.

Jack and Frank had recently returned with a British convoy from America. They were in Dover at the time. From his sick bed in a hospital, the captain of the Plymouth had appealed to the British naval authorities. In spite of the fact that he was in no condition to leave when he received his orders, he did not wish to deny his crew the privilege of seeing active service, which the call to Liverpool, he knew, meant.

The captain's appeal had been turned over to Lord Hastings, now connected prominently with the British admiralty. Lord Hastings, in the early days of the war, had been the commander under whom Jack and Frank had served. In fact, the lads were visiting the temporary quarters of Lord Hastings in Dover when the appeal was received from the commander of the Plymouth.

"How would you like to tackle this job, Jack?" Lord Hastings asked.

"I'd like it," the lad replied, "if you think I can do it, sir."

"Of course you can do it," was Lord Hastings' prompt reply. "I haven't sailed with you almost four years for nothing."

"You mean, sir," replied Jack with a smile, "that I haven't sailed with you that long for nothing."

"That's more like it, Jack," put in Frank laughingly. "I've learned a few things from Lord Hastings myself."

"It is hardly probable," continued Lord Hastings, "that your promotion has been unearned, Jack. No, I believe you can fill the bill."

"In that case, I shall be glad to take command of the Plymouth temporarily, sir."

"And how about me?" Frank wanted to know. "Where do I come in, sir?"

"Why," said Lord Hastings, "I have no doubt it can be arranged so you can go along as first officer. I understand the first officer of the Plymouth is also under the weather."

"But isn't all this a bit irregular, sir?" Jack asked.

"Very much so," was Lord Hastings' reply. "At the same time, many precedents are being broken every day, and I can see no reason why two British officers cannot lend their services to an ally if they are asked to do so."

"It is a little different with me, sir," said Frank. I'm an American."

"All the same," said Lord Hastings, "you're a British naval officer, no matter what your nativity."

"That's true, too, sir," Frank agreed. "I haven't thought of it in just that way."

"Well," said Lord Hastings, "I shall report then that Captain Templeton and First Lieutenant Chadwick will go aboard the Plymouth this evening."

"Very well, sir," said Jack.

This is the reason then that Jack and Frank found themselves aboard an American destroyer in the Irish sea.

Frank Chadwick, as we have seen, was an American. He had been in Italy with his father when the great war began. He had been shanghaied in Naples soon after Germany's declaration of war on France. When he came to his senses he found that his captors were a band of mutinous sailors. Aboard the vessel he found a second prisoner, who turned out to be a member of the British secret service.

Frank met Jack Templeton, a British youth, aboard the schooner. Jack came aboard in a peculiar way.

The schooner, in control of the mutineers, had put into a north African port for provisions. Now it chanced that the store where the mutineers sought to buy provisions was conducted by Jack. The lad was absent when the supplies were purchased and returned a few moments later to find that the mutineers had departed without making payment.

Jack's anger bubbled over. He put off for the schooner in a small boat. Aboard, the chief of the mutineers refused the demand for payment. A fight ensued. Jack, facing heavy odds, sought refuge in the hold of the vessel, where he was made a prisoner.

During the night Jack was able to force his way from the hold into the cabin where Frank and the British secret service agent were held captives. He released them, and joining forces, the three were able to overcome the mutineers and make themselves masters of the ship.

Now Jack Templeton was an experienced seaman and knew more than the rudiments of navigation. Under his direction the schooner returned to the little African port that he called home. There the three erstwhile prisoners left the ship to the mutineers.

Later, through the good offices of the British secret service, Frank and Jack made the acquaintance of Lord Hastings, also in the diplomatic service. They were able to render some service to the latter and later accompanied him to his home in London. There, at their request, Lord