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.
CHAPTER 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.