o be almost a
reality, for it was raining and the water was coming in through the
flimsy roof of their shelter.

"What's the matter?" asked Andy sleepily as he heard his brother moving
about.

"It's raining a flood! I'm drenched and so must you be."

"That's right, I am pretty wet. What had we better do; make for the
_Gull_?"

"What, in this storm and darkness? No, but I think there's a cave near
here. We can go in that and keep dry, at any rate."

"Go ahead, I'm with you."

They were fortunate in finding a small cavern, and in it was a supply
of dry wood. They made a fire, though the smoke was almost as bad as
the dampness, but it served to get rid of that chilly feeling.

It was still raining when morning came, but the boys were more cheerful
with the appearance of daylight, though they had to breakfast on cold
food, for all the wood was wet, and the supply in the cave had been
burned.

"Oh, well, we can go back to our first camp and row out to the _Gull_
pretty soon," remarked Frank. "Let's hurry on with our search now."

"I'm afraid it isn't going to amount to anything," declared Andy.
"That man isn't here, and he hasn't been here. Captain Trent's theory
was all right, but it didn't work out."

"Oh, I'm not going to give up yet," insisted Frank. "We have a good
part of the island to explore yet."

But, as they went farther on, it became more and more evident that
there was no one on the island but themselves--that is, unless the
mysterious man was hidden somewhere between them and their first
camp--a distance of about a mile.

"We'll cover that, and then all there is to do is to sail back home,"
proposed Andy, as they started on the last lap of their search, after
eating a hasty lunch. It had stopped raining, for which they were very
thankful.

There was one more cave to explore, and this was soon proved to contain
nothing but a colony of bats, which they disturbed with their flashing
light.

"I hope our boat's safe," mused Frank as they headed for the place
where they had left it. "I don't fancy swimming out to the _Gull_."

"Oh, it will be all right," asserted Andy confidently. "There she is,"
he added a moment later, as he made the turn around a jutting rock.
"She hasn't been moved since we slept under her."

Together they approached their boat. As he neared it Frank looked
critically at some marks in the wet sand--a series of footprints all
about the craft.

"Look!" he exclaim