"As we entered the only open shaft leading out of the chamber, a high-pitched musical note became audible. I wondered if our movements had sounded some mysterious warning. As we continued on into the luminous tunnel that glittered with deposits of priceless gems, the musical note rose higher and higher so that it seemed to tax the sense of hearing to its uttermost. Questioningly I turned to Sands. One of his trembling hands was chafing his temples with thumb and forefinger. The sound gradually became a wail like the metallic scream we had heard before entering the cave that led down to the chamber. "Suddenly I became aware that Sands had broken the influence that had held him! With a frenzied scream he leaped aside and away from me. I gazed in wonder at the man as he crouched like a beast at bay. I expected him momentarily to spring at my throat. But he finally recognized me and became controlled when I assured him the Jovians were not in sight. His first questions were of Allie Lane. Had he really seen her, he wanted to know, or had he been suffering from a brain fever? Was she really alive--as beautiful as ever? I assured him that she was. "'Lord!' he gasped, shuddering. 'That noise would drive a man insane!' "'Yes,' I whispered softly, 'But you ought to thank it for bringing you to your senses!' "'What do you mean?' he asked, blankly. "'Don't you know that the Big Chief of these freaks bounced you for jumping onto the platform?' "'I don't remember anything but that I'd seen or dreamed I've seen Allie Lane alive!' he said, disconsolately. "'Well,' I explained, 'The High Chief, who calls himself by the name of Abaris, didn't like the idea of you getting familiar with Allie and he knocked you out cold. I thought he killed you and he might have at that had he wanted to. I thought you were a goner!' "'He's got a hell of a nerve then!' he exploded, his face twitching in terrible rage that under the glow of green made him almost as grotesque as Abaris himself. 'I've loved Allie Lane all my life and now that I've found her nothing but death will stop me from having her!' "'We haven't found her yet, Sands,' I reminded him softly. 'She's somewhere down this tunnel! I think we ought to get to her as soon as we can. Those devils are going to leave here! Abaris'll probably take Allie with him!' * * * * *