He switched it on, and saw that, as he had imagined, he was in a cave, through the roof of which the hole showed, dark and round. “I wonder if this is the robbers’ lair,” thought the boy, flashing the torch around. But there was nothing at all in the rocky cave, whose rugged walls threw back the gleam of the torch.

Mike’s feet appeared at the bottom of the hole and the boy jumped down beside Jack. Then came Paul. They all stood together, examining the cave.

“It doesn’t look as if anyone lives here at all,” said Mike. “There are no beds where you might expect the robbers to sleep, not a sign of any pot or pan. I don’t believe this is their lair.”

“Well, what is it, then?” demanded Jack. “I saw them go down here, didn’t I? Goodness knows how Ranni and Pilescu were taken down, with their hands tied! Where can they be?”

“They’re nowhere here at all,” said Paul, flashing his torch into every corner. “It’s odd. What can have become of them?”

It really was a puzzle. Jack began to go round the little cave, his footsteps echoing in a weird way. He flashed his torch up and down the walls, and suddenly came to a stop.

“Here’s another way out!” he said. “Look! It’s quite plain to see. I’m surprised we didn’t see it before when we shone our torches round.”

The boys looked. They saw that halfway up the opposite wall of the cave was a narrow opening. They jumped on to a ledge and peered through it. It was plain that it led out of the cave, and was a passage through the rock.

“Come on,” said Jack. “This is the way the robbers must have gone. I’ll go first!”

He was soon in the passage that led from the cave. He flashed his torch in front of him. The way was dark and rough, and the passage curved as it went, going downwards all the time. Where in the world did it lead to!