," said Billy firmly. "Dog or no dog, I'm not going back till
I've found out where they've hidden Hugh!"

If Billy had only known that Hugh was locked in that further cabin!
If Hugh had only been able to communicate with his friends on
picket duty! How much trouble would have been avoided,---yet what
an adventure they would have missed!

Dave now explained to Billy that his purpose had been to purloin
the sailing canoe, so that the smugglers on shore would be dependent
on a boat from the _Esperanza_ to take them and their goods away.
This would enable the crew of the _Petrel_ to intercept the smugglers
as soon as they landed. But now, with the appearance of this man in
the canoe, Dave's plan seemed about to be thwarted.

* * * * * *

Meanwhile, what of the others who remained on the peninsula?

More than an hour passed before any one saw a suspicious figure on
the landscape. Then Alec, whose post was farthest removed from the
landing place, suddenly caught sight of two men walking along the
shore. They were carrying the same battered tin box which he and
Billy had found half buried in the sand, many hours ago. Evidently
the box was heavy, for they appeared to stagger with its weight.

Alec raised his voice in the weird, low call of the otter. As his
patrol was named after that animal, he knew that Chester, also of
the Otter patrol, would recognize the signal. In this case it meant
"Danger. Look around you."

From a distance, hidden behind a clump of palmettos, Chet responded
with the same call twice, in quick succession.

But the men carrying the box heard the calls. They knew it was still
too early in the afternoon for otters to be hunting so noisily, and
they were surprised, startled, suspicious. To Alec's dismay, they
dropped the box, stood still, and stared all around them. Alec lay
flat on the ground, trusting that his khaki suit and brown flannel
shirt would help him to escape observation. At the same time he
dread lest one of the other pickets would be seen too soon.

The two men, after gazing out to sea as if expecting to sight a
vessel on the horizon, picked up the box and came on again. Every
step brought them nearer Alec, who of course had been told to allow
all strangers to pass unchallenged---until to-morrow.

"Hark!" said one of the men, listening. "That's Rover barking!"

"He barks at nothing!" declared the other. "Eet is a fool dawg, zat
Rover! I know heem, ye