CHAPTER 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 some one prowling around here."
"What's that?" called out Frank, from the darkness.
"There was some one 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 reallywassomebody. 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. Iheardhim 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 foot-prints 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 to-night, 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 patch 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 was well illuminated as the boys slowly picked their way among the rocks. The far wall of the huge cavern was still invisible.
"This is a whopper!" said Joe, in an awed whisper.
Frank stopped, with a murmur of annoyance.
"What's the matter?" asked Chet.
"My flashlight. It's on the blink."
Vainly, Frank tried to coax a gleam from the refractory instrument. It was no use. He put the light in his pocket.
"I'll have to fix it to-morrow," he said. "It won't work any more to-night by the looks of things."
"Here's mine," offered Biff.
But Frank declined.
"No thanks. One of you chaps take the lead for a while. I can follow easily enough."
Joe took the lead, as Frank suggested, and the little party moved on again.
It was rough going. The floor of the cave became piled high with rocks, evidently from cave-ins that had occurred in times past; in other parts it was pitted with little gullies and holes. In trying to avoid these, the chums gradually became separated.
Frank stumbled along behind. He felt the loss of his flashlight, but said nothing, relying on finding his way by the radiance provided by the lights carried by the others.
Soon, however, the three lights became scattered. Joe had gone to one side to avoid a huge boulder; Chet had gone to the other side and encountered a pit that prevented him from returning to Joe's trail; Biff had tried to follow Chet and had blundered into a labyrinth of rocks.
Frank stood uncertainly for a moment, then called out.
"We're getting separated. Wait for me."
The walls of the great cave flung back the echoes time and again.
He heard Joe shout:
"Where are you?"
Had it not been for the glow of Joe's light he would never have known where the voice came from because the echoes confused him, and the tones seemed to come from all parts of the cave.
Frank realized that his own shouts would cause the same confusion to the others.
"Don't move around!" he called, "I'll head toward one of the lights."
But evidently his order was misunderstood, for one of the lights began to move erratically through the darkness.
Frank went forward. He blundered against a rock and fell, bruising his knees. He got to his feet and went on, still in the direction of the nearest glow.
He was confused by the moving lights. Had his own flashlight not failed him this would not have happened.
Suddenly, he stumbled.
He lurched forward. His foot groped wildly for the firm rock, but there was nothing to stop his plunge. He had fallen into a pit.
Straight down through the blackness he hurtled, with a wild cry of terror.
The others heard that cry. They heard a far-off crash, and then the clatter of falling rock.
Joe was the first to shout.
"Frank!" he called.
There was no answer. The echoes rang back.
Although the other boys shouted time and again there was no answer from Frank Hardy. They searched frantically, casting the beams of their lights here and there, but they found no trace of him.