All the boys' work was undone. The barrier was now larger than it had ever been.
"That fixes it!" said Frank gloomily.
The ledge of rock that had given way was of such extent that it was impossible for any one to move it. Their path was completely blocked.
"No use working at that any more!"
Frank sat down on a rock, regarding the impassable heap.
"Buried alive," he remarked, at last.
"No one will ever find us here."
The boys realized the gravity of their plight. No one knew they were in the tunnel. No one had seen them enter. If they perished here, their bodies might never be recovered.
"Think we ought to start calling?" asked Joe hopefully.
"Looks as if we'll have to do something. Perhaps if we do call, the men won't hear us."
"How about going back along the tunnel? There was still a sort of opening, you remember."
"It's our only chance."
Frank had little hope that the tunnel had another outlet. However, he grabbed up the flashlight and the boys picked their way back along the rocky passage.
When they came to the place where the tunnel had seemed to end, they surveyed it dubiously.
