"I can't go any farther. The passage ends here in a solid rock."
"Then we'll have to go back. I thought he was fooling us. He wanted to get us in some side chamber, so he could make his escape from the entrance. Hurry back."
They fairly ran to the other end of the passageway, retracing their steps. This time Frank was ahead. Suddenly he came to a halt.
"Well, why don't you go on?" asked Andy.
"I can't. There's a big rock here."
"A rock? There wasn't any there when we came in."
"I know it, but it's fallen down since. The passage is closed."
"Closed!" gasped Andy. "Then I know what happened. That was the noise we heard. That man toppled this rock down to trap us here. We're caught, Frank! Caught!"
For a moment the older brother did not answer. Then he replied:
"It does looks so. But we'll try to shove this stone out of the way.
Come on, lend a hand."