“Well, that settles it. This is a chart of the caves. What! Eighteen of them all in a row, some short, some deep, some branching, same as we saw them. It’s a map, and here’s a cross on it. What’s the cross for? It is placed to mark one that is much deeper than the others.”

“One that goes through,” I cried.

“I believe our young friend has read the riddle,” said Challenger. “If the cave does not go through I do not understand why this person, who has every reason to mean us well, should have drawn our attention to it. But if it does go through and comes out at the corresponding point on the other side, we should not have more than a hundred feet to descend.”

“A hundred feet!” grumbled Summerlee.

“Well, our rope is still more than a hundred feet long,” I cried. “Surely we could get down.”

“How about the Indians in the cave?” Summerlee objected.