The fire was a scarlet eye in the blackness of the cave. Beyond the entrance, rain still poured in a seemingly endless torrent and the surf roared dully.
An hour passed. Two hours.
Joe, who had been sleeping soundly, was awakened. At first he did not realize where he was, could not imagine why he was sleeping on the ground, wrapped in a heavy blanket, and then it gradually came back to him and he remembered about the cave.
He was just about to turn over and go to sleep again, wondering vaguely what had aroused him, when he heard a footstep.
It came from close by.
He listened, and then he heard it again. Someone was moving cautiously about in the darkness.
Joe raised himself on one elbow and peered into the gloom. But he could see nothing. However, he reasoned that it was probably only one of his chums.
When he heard a rustle, he spoke.
“Is that you, Frank?”
The words rang out clearly in the silence of the cave.
But the consequence was surprising. Instead of the reassuring voice of his brother, Joe heard a muffled exclamation, quick footsteps as someone ran across the floor of the cave, and then the crash of a fallen rock.
XII
A Disappearance
“Who is that?” demanded Joe Hardy, scrambling to his feet.
There was no answer. He heard the sound of running footsteps gradually growing fainter.
“Hey, there!” he shouted, now thoroughly aroused. “Fellows! Wake up!”
He stumbled about in the darkness, trying to find his flashlight and his chums. Then he heard Chet’s sleepy voice:
“What’s the matter? It isn’t morning yet. Lemme sleep.”
“Wake up! There’s someone prowling around here.”
“What’s that?” called out Frank, from the darkness.
“There was someone else in the cave just now. He woke me up.”
“Perhaps it was only Biff. Hey, Biff!”
A deep sigh. Then Biff mumbled:
“Whaddaya want?”
“Wake up.” Frank switched on his flashlight and he turned it on each member of the startled group. “Everybody here?”
“Sure!” replied Biff, sitting up in his blanket. “What’s wrong?”
“Joe says somebody was prowling around the cave.”
“It wasn’t me. I’ve been sleeping like a log.”
“It wasn’t me either,” spoke up Chet.
“I guess I was right, then,” declared Joe. “There really was somebody. I thought for a minute it might be one of you playing a trick on the rest of us.”
“We’re all accounted for,” said Frank. He got up and tossed a stick of wood on the embers of the fire. In a few minutes it began flaming up brightly, casting a circle of illumination through the cave. “Tell us about it, Joe.”
Joe thereupon told of hearing the mysterious footsteps in the cave, of calling out and of hearing the exclamation, the crash of the rock, and the running footsteps as the intruder fled.
“Did he go out the front way?”
Joe shook his head.
“No. He seemed to go farther into the cave, toward the back.”
“Well, then,” said Frank decisively, “we’ll just go and look for him. If he went that way, he’s in the cave yet.”
“Aw, let’s look for him in the morning,” protested Chet, as he rubbed his eyes. “I think Joe was dreaming.”
“It was no dream. I heard him walking around. It wasn’t any of us, so it must have been a burglar—or somebody.”
“What would a burglar come around here for?”
“Perhaps it’s the chap who piled up all that wood,” said Frank. “Maybe this is his cave and when he came in and heard Joe call out he got frightened and ran.”
“That sounds more reasonable. Anyway, we’ll take a look around for him. He can’t be far away.”
The boys hurriedly dressed. They were soon wide awake, excitement having banished all desire for further sleep.
“We were going to explore in here, anyway,” said Frank, as he took his flashlight and led the way toward the back of the cave.
The boys confronted an arch in the rock, an opening that seemed to lead into a tunnel. They approached it cautiously, and Frank often turned the light on the floor to make sure that no pitfalls lay before them.
Frank went into the tunnel first. In single file, the others followed.
It was about fifteen feet in length and about six feet high. As the floor was of solid rock, they were unable to find any footprints that would serve to prove that the intruder had passed that way.
The tunnel led to another cave.
“Why, there’s a regular chain of caves in here!” exclaimed Joe, as the boys stepped out into a massive underground chamber.
“Our cave was only the beginning,” said Chet.
In the glow of their flashlights they saw that the cave in which they now stood had a number of dark openings in the walls. These were, presumably, tunnels leading into further caves beyond.
“There are a dozen different passages out of here. Our friend might have taken any of them,” said Frank.
“We’ll tackle the biggest,” suggested Biff.
“Good idea. If we don’t get anywhere, we’ll try the others.”
The largest tunnel was immediately ahead. Frank, accordingly, stepped into the gloomy passage. The others followed.
“When I was going to sleep tonight, I never thought I’d wake up and take part in an exploring trip underground before morning,” observed Chet.
Frank gave an exclamation.
“Here’s what we were looking for!” he cried.
“What?”
“A footprint.”
The others crowded around him.
Clearly discernible in the radiance of Frank’s flashlight, the lads could see the imprint of a boot in a pitch of wet sand on the floor of the tunnel.
“Looks like a fresh track, too,” said Joe.
“We’re on the right trail. Let’s keep moving.”
With increasing excitement, the chums pressed forward and in a few moments Frank stepped out of the passage into another cave. This was the largest cave of all, an enormous underground vault, and even the flashlight beams failed to reveal the rocky walls and ceiling.
The floor was rough and broken fragments of rock were strewn about.
“Watch your step,” warned Frank, as he made his way across the cave.
The others had flashlights and the floor
