"That's so. But, speaking of night, what are we going to do about sleeping?"

"Under our boat, with our blankets spread out on the sands," said the younger lad. "It's plenty warm enough."

It was not a half bad way to spend the night, especially as the overturned rowboat kept off the chilly dew. Soon the two brothers were soundly sleeping. They did not bother to keep a watch and even allowed the fire to die out, taking the precaution, however, to put some wood under the boat, where it would be dry in case of rain in the night.

"Well, now for another try at the mysterious man!" called Frank, as he crawled out from under their shelter the next morning. "Maybe we'll have better luck to-day."

They set off directly after breakfast, and took with them their blankets and a supply of food. For they intended to make a half circuit of the island that day, and they figured that night would find them too far away from their camp to make it practical to return.

"We'll eat and sleep wherever we are when it's dark," decided Frank.

Their search that day was as fruitless as fore. Not a vestige of the man or boat to be seen. They made a sort of shelter of driftwood and seaweed before darkness fell, and built a rousing fire in front of it, where they sat and talked until it was time to turn in.

"I don't like the looks of the weather," remarked Frank as he wrapped up in his blankets.

"Why not?" his brother wanted to know.

"It looks like rain, and if it does we're going get wet."

"Oh, I guess not," said the younger lad easily. He never looked for trouble.

It was along toward morning when Frank awoke from a troubled dream that he was standing under a shower bath. He found it to 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," a.s.serted 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 exclaimed, pointing to them.

"Well, what about it?" asked Andy calmly. "You and I made them."

"It rained since we were here night before last," said Frank in a low voice, as if afraid someone would hear him. "Our footprints would have been washed away. Someone has been here since--a man----"

He paused and looked down the beach. An indefinable something had attracted his attention. The next moment he grasped Andy by the arm.

"There he is!" he exclaimed.

And there, about a quarter of a mile away was a man, standing beside a big wrecked motor boat that was drawn up on the beach. It was the mysterious personage for whom the Racer boys were searching.

CHAPTER XIX

IN THE CAVE

For a moment Frank and Andy were so surprised that neither one of them could think of anything to say. It seemed almost impossible that their search should be rewarded just at the time when they had given it up.

Yet there was no mistake. There was the man they wanted. At least they a.s.sumed so, for they could not make out his features at that distance. At any rate, there was the wrecked motor boat, and the tall man was critically inspecting it.

"Look! Look!" was all Andy could whisper.

"Yes," a.s.sented Frank. "Now if he'll only let us get within talking distance, and not run as he always does, we may learn something. I wish we could steal up on him quietly."

"No chance of that, I'm afraid. He knows we're here. It was he who was walking around our boat."

"Sure; and he knows it's the one from the _Gull_. Well, the only thing to do is to go right up to him. I wonder what he wants with that boat, anyhow? See, he's poking into it as if there were gold or diamonds concealed in it."

"Perhaps there are. Maybe that's the mystery," said the younger Racer lad eagerly.

"Oh, you got that out of some of the books you read. But I can't understand how we could have missed him."

Andy did not answer. Instead he grabbed his brother and pulled him down on the sand behind the boat. It was only just in time, for the man had turned and was gazing back toward the overturned craft.

"I hope he didn't see us," whispered Andy.

"We must lay low until we think of some plan. Maybe he'll get down inside the motor boat and then we can get up to him before he knows it.