he whole world seemed to be filled with thunder when David Guinness came back to consciousness. He opened his eyes and stared up into a darkness to which it took him some time to accustom himself. When he did, he made out hazily that he was lying on the floor of a vast dark cavern. He could dimly see its jagged roof, perhaps fifty feet above. There was the strong smell of damp earth in his nostrils; his head was splitting from the steady drone in his ear-drums. Suddenly he remembered what had happened. He groaned slightly and tried to sit up.
But he could not. His arms and legs were tied. Someone had removed him from the earth-borer and bound him on the floor of the cavern they had plunged into.
David Guinness strained at the rope. It was futile, but in doing so he twisted his head around and saw another form, similarly tied, lying close to him. He gave a little cry of relief. It was Sue. And she was conscious, her eyes on his face.
She spoke to him, but he could not understand her for the drone in his ears, and when he spoke to her it was the same. But the professor did not just then continue his effort to converse with her. His attention was drawn to the borer, now dimly illuminated by its portable light, which had been secured to the door. It was right side up, and appeared to be undamaged. The broad ray of the searchlight fell far away on one of the cavern's rough walls. He could just make out James Quade standing there, his back towards them.
He was hacking at the wall with a pick. Presently he dropped the tool and wrenched at the rock with bare hands. A large chunk came loose. He hugged it to him and turned and strode back towards the two on the floor, and as he drew near they could plainly see a gleam of triumph in his eyes.
"You know what this is?" he shouted. Guinness could only faintly hear him. "Wealth! Millions! Of course we always knew the radium was here, but this is the proof. And now we've a way of getting it out—thanks to your borer! All the credit is yours, Professor Guinness! You shall have the credit, and I'll have the money."
Guinness tugged furiously at his bonds again. "You—you—" he gasped. "How dare you tie us this way! Release us at once! What do you mean by it?"
