n daylight, the boy scouts on picket duty would have seen
the same long, low, gray craft something like a built-for-speed tug
boat, which had surprised Captain Vinton when it first appeared among
the Keys, now coming to anchor outside Durgan's Cove, in the darkness.

As it was, however, they could see nothing after the _Esperanza's_
lights went out; but, waiting impatiently, they presently heard the
dip of oars, the faint rattle and squeaking of row-locks, and then
a low whistle which seemed to come out of the quiet that brooded over
the ocean.

"It's a boat from the _Esperanza_!" muttered Norton. "One of us had
better steal back to the camp, and see what our friends are doing.
Dave, you-----"

"Oh, let me go!" interposed Alec. "I can run the motor boat over
to our camp and bring the soldiers here in about twenty minutes---or
less."

"My dear boy, those fellows out there who are coming ashore would
be sure to hear a motor boat," declared Norton. "Even with a
muffler on, the sound would reach them."

"But it's the only boat we have, .sir," said Mark, "and, when
all's said, that's why Billy and Dave took it---to bring the men
over sooner than they could tramp across these flats."

"You're right, Mark; but-----"

Again he was interrupted by one of his eager young friends---Chester,
this time.

"Perhaps Dave could pole the motor boat over," he suggested.

"Could you, Dave? It's not a large boat by any means."

"Uh-huh, sure!" assented the guide. "But slow work---lose heap
time."

"No matter. Anyway, we've got to give those fellows time to land and
to get to the cabins before we surround them. Go ahead, Dave; and
Alec, you go with him to run the boat back. I guess you know more
about a gasoline engine than any of us. Hurry now---and good luck!"

The intrepid young scout needed no urging. Before Dave had found a
suitable pole, Alec had taken his place at the stern and was pointing
her in the direction of the peninsula on which Lieutenant Driscoll
and his men were waiting.

In a few minutes Dave was pushing the light but substantial launch
along the waterway, and almost immediately it disappeared from sight,
swallowed up in the darkness.

It returned in about half an hour, crowded to the gunwales, carrying
the dozen men. In the meantime, a rather startling incident had
occurred.

Dave and Alec had been gone only ten minutes or so, when the assembled
pickets observed a bright light burst forth fr