The Hardy boys knew that the Shore Road bluffs, in certain places, contained caves and passages, some of which had never been entered. Although like most Bayport boys, they had done a certain amount of exploring along the beach, they had never heard of the existence of this underground labyrinth. It seemed strange to them that so elaborate a series of caves had never been explored and their existence was comparatively unknown.
“Wait until Bayport hears of this!” Joe said. “Let’s get out of here and hurry back to town.”
“I suppose we should,” Frank admitted. “I’d like to know where those men went.”
“If we go any farther they may catch us, and then we’d be out of luck.”
“But if we start back to town we’ll have to walk, and they might all clear out in the meantime. It would be a few hours before we could get back here with the police.”
“We’d have the satisfaction of recovering the cars, anyway,” Joe pointed out. “I believe in playing safe.”
“I’d like the satisfaction of rounding up this gang as well.”
Frank advanced toward the opening at the far side of the cave.
“I think I’ll just poke along in here a little way and see where it leads,” he said.
Joe was dubious. He was of a more cautious nature than his brother, and was satisfied to let well enough alone. They had found the missing cars. This alone was sufficient, he reasoned. Having come this far without mishap he did not like to risk spoiling their success. However, he followed Frank into the tunnel.
It was narrower than the one which had led them to the cave, and its sides were rocky and uneven, while the roof was low. It was quite evident that none of the cars could have been driven through this narrow space, and as the boys went on they found that the roof was lower and the walls even closer together.
Finally, the flashlight showed them that it was almost impossible to continue, as projecting rocks jutted out and there was just enough space to admit passage of one person. Beyond that, the tunnel seemed to close altogether.
“Guess this is a blind alley,” said Frank. “We may as well turn back.”
He handed the flashlight to Joe, who led the way on the return trip through the tunnel.
Suddenly there was an uproar immediately ahead, a clamorous, deafening crash. The boys jumped with astonishment. In the darkness of the subterranean cavern their nerves had been keyed up to a high pitch, and this tremendous clatter was so unexpected in the dead silence that had surrounded them that they were almost paralyzed with momentary fright.
There followed a rattling and bumping of rocks, and then silence once more.
“What was that?” exclaimed Joe, recovering from his scare.
“Sounded to me like a fall of rock.” Frank’s voice was shaky, for he had a suspicion of what had actually happened.
“It seemed mighty close.”
“That’s what I’m afraid of. It may have blocked up this tunnel.”
Hastily, the boys went forward. In a few moments the flashlight revealed a sight at which their hearts sank.
The passage before them was completely closed up!
Great boulders, ledges of rock, and a heavy downpouring of earth formed an apparently impenetrable barrier ahead. A loose stone, no doubt dislodged when they went by a short time before, had given way and had brought down this miniature avalanche from the roof and sides of the tunnel.
“We’re trapped!” Frank exclaimed.
XVIII
The Auto Thieves
The cave-in had imprisoned the Hardy boys.
The flashlight revealed not a single opening. The tunnel was blocked up, and for all the boys knew the barrier continued right to the outer cave.
“Now we’re in for it,” remarked Joe dubiously.
The boys realized that there was nothing to be gained by shouting for help. Even if their cries were heard, which would be unlikely with that solid mass of rock before them, it would only bring the auto thieves upon them.
“We’ll have to work fast,” said Frank. “There isn’t any too much air in this place now, and if we don’t get that rock cleared out of the way we’ll be smothered.”
“Do you mean to say we’ll have to move all that rock aside?”
“What else is there to do?”
“It might take hours.”
“That’s better than dying in here,” returned Frank philosophically. “You hold the light and I’ll get busy.”
He flung off his coat and attacked the formidable barrier.
Starting at the top, he moved rock after rock aside, placing them on the floor of the tunnel. The work was slow, and he seemed to make little progress. For, as the rocks were taken away, they showed only more rocks behind. It was evident that the cave-in had been of considerable extent.
Joe became impatient.
“I feel useless,” he said. “You hold the light for a while and let me work.”
“Put it in a ledge some place and we can both work.”
Joe hunted around and managed to find a convenient ledge of rock on which to rest the flashlight. Its beam was directed at the barrier and, rid of the encumbrance, Joe was then able to lend a hand to the work of removing the debris.
Patiently, the brothers toiled, lifting aside the rocks and putting them back on the floor. Every little while a fresh shower of dirt and stones would come rattling down from the roof. The task seemed hopeless.
“Looks as if this goes on for yards,” panted Joe wearily.
“We might get out in a couple of years,” Frank said, resting for a moment. “Still, if we can only clear a small opening it’ll be enough to let us out.”
He attacked the barricade again with renewed vigor.
Wrenching at a large rock, he tugged and pulled until it became dislodged from the surrounding debris. Frank was just dragging the huge stone away when there came a warning rumble, a cry of alarm from Joe, and he leaped back.
He was just in time.
With a crash, a large section of the roof caved in, a flat ledge of rock just
