few hours before, it gave Slim a creepy sort of feeling.

Then all sound ceased. Try as hard as he would, he could not hear a
thing. He rose from the chair and went closer to the intervening door.
All was silent!

A few seconds later the captain and lieutenant, accompanied by Jerry,
came hurrying into the room. Without an instant's delay the captain
turned the knob and they entered the battery room, switching on the
light at the same time.

Apparently not a thing had been touched, but the outer door was ajar.
The lieutenant jumped to it and peered out, but no one was to be seen.
He closed and locked the door and began an inspection of the batteries.

"Everything seems to be all right," he said finally; and then, his eyes
traveling to the table, he stopped short.

"The wireless instrument," he gasped. "It's gone!"

"Where was it left?" the captain demanded sharply.

"On that table there," Lieutenant Mackinson answered. "I placed it there
myself, as you probably will remember, just before we went out
together."

"I remember," the captain admitted.

"That spy has been back," the junior officer continued. "Back in this
very room after his instrument, and he intends to use it yet if he
can!"

CHAPTER VII

THE TIMELY RESCUE

It was no pleasant thought to contemplate the presence of a bold, even
desperate, agent of an enemy government, on board an American transport
carrying approximately two thousand souls.

That he was capable of going any lengths, if necessary, already had been
proved; and the evidence of his evil genius might come in horrible form
at any instant.

Nevertheless, neither the excitement nor the potential danger of the
situation was sufficient to prevent Jerry and Slim from taking a full
eight hours of much-needed sleep, while Lieutenant Mackinson, Joe and
three other officers whom the captain had taken into his confidence in
the matter, followed out every possible clue in pursuit of a solution of
the baffling mystery.

The record of every enlisted man and officer on the vessel had been most
carefully probed, without building up enough suspicion to warrant the
singling out of any individual as the probable offender.

Likewise an investigation of the members of the crew had failed to
develop anything tangible, even directly suspicious. It was a case of
watch everybody, take every precaution, and be prepared for anything.
Only nine men on the vessel, however, including the spy himse