“I don’t like the idea of stayin’ too close to the cave,” growled the man who had been by the fire. “If anybody comes around here and should find us they’ll have to look some to find them as long as we’re not near the cave, see?”
“That’s all right, Pete,” retorted Red. “If anyone comes on this island we’ll know of it in lots of time to clear away from the cave. We may as well keep cool.”
There was a grumbled assent from Pete, and then the Hardy boys heard sounds of receding footsteps as the quartette strode off through the grass. They waited until the men were out of earshot, then peered through the undergrowth.
“Shall we follow them?” asked Joe eagerly.
“You bet we will! I want to know where this cave is that they’re talking about. And I want to know who the prisoners are that they mentioned.”
“Do you think it really could be Chet and Biff?”
“I’m almost sure it is. Didn’t you hear the fellow saying that the prisoners kept insisting that there’d been a mistake? We’ve figured it out right all along. They captured Chet and Biff in mistake for us.”
The Hardy boys began moving through the undergrowth on the trail of the four men. They crouched down and kept to the shelter of the bushes so that they were able to proceed at a good rate of speed without exposing themselves to view.
“If we can only get into the cave and get Chet and Biff free!” exclaimed Joe.
“It won’t be any too easy. They seem to be guarding them pretty closely. First of all, we’ve got to be certain that it’s them.”
“I don’t think there’s any doubt of that. Everything hangs together too well. If we could get them out we could run for the boat and get them away to the mainland.”
“That’s what we’ll have to plan on. But the main thing is to find this cave.”
“Yes, of course.”
The four men in the lead had entered the outskirts of a small grove toward the center of the island. Frank could just see the head and shoulders of the last man disappearing into the woods. He marked the spot where the fellow had entered the grove and the Hardy boys made toward it. They found it comparatively easy to follow the trail, for the others had beaten down the grass and twigs in passing, and in a few minutes they had reached the grove.
“Go slow,” cautioned Frank, as they entered the shadow of the trees. “They may have seen us crossing the clearing.”
They listened for a moment. They could hear the crashing of branches and the crackling of twigs, the distant hum of voices, as the quartette continued through the woods, so they went ahead.
The wood was steaming hot and the ground was dank underfoot. The grass was long and the leaves of the trees drooped of their own weight. Once Frank saw a blacksnake scurrying away through the grass, but none of the serpents molested them. The path the boys followed was beaten down by the feet of the men ahead and they made easy progress until at length the sight of a clearing ahead warned them to again exercise caution.
They crept along through the trees and underbrush until the clearing came fully into view. It was at that part of the interior of the island where the swamp gave way to the rocks, and the grassy clearing led in a gradual slope to a high wall of rock, at the base of which was the mouth of a cave. As the Hardy boys watched, they could see the four men at the opening. One of the fellows, a tall, dark man, was mopping his brow with a handkerchief, while another, a man with a shock of red hair, was just going into the cavern. The other two had flung themselves down on the rocks in the shadow of some overhanging bushes.
“So that’s the cave!” exclaimed Frank.
“I wonder if Chet and Biff are inside.”
“Most likely. I wish we could get a little closer.”
“Too dangerous. They can see anyone coming into the clearing.”
This was true. The cave had evidently been chosen not only for its possibilities as a shelter but for its defensive virtues as well. It was plainly the hangout of the gang.
“We’ll have our work cut out for us to get in there,” muttered Frank. “The place is too much in the open. Our only chance is to wait until some of them go away.”
“We might be able to sneak up closer when they’re asleep.”
“We’ll try it. The only thing for us to do right now is wait until they’re all asleep.”
The boys settled themselves down in the bushes, prepared for a vigil until nightfall. It was now late in the afternoon, and when Frank glanced up at the sky he saw that clouds had gathered. The sunshine had gone, for a dense black cloud obscured the sun. The sultry and oppressive heat of the afternoon had evidently presaged a storm.
“Looks like rain.”
“It sure does,” agreed Joe, looking up.
As though in corroboration, there was an ominous rumble of thunder. The wind had died down. Every leaf, every blade of grass was still. The clouds were massing silently.
However, the storm held off, and although the sky was overcast and threatening, twilight fell without rain. Frank and Joe, from their hiding place in the bushes, watched the four men moving aimlessly about the cave that afternoon. Two of them had remained inside the cave for a long time while the other pair chatted on the rocks outside.
Night came at last. From the interior of the cave came the flicker of flames, and the Hardy boys knew that the gang was making a fire for the night.
The heat was still oppressive. Darkness fell without moon or stars.
“We’ll soon be able to creep up on them now,” said Frank. “If we can only get close enough to hear what they’re saying we’ll probably
