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