The leader broke in. "We'll circle again. Be careful of that Project bunch--they'll be using ordinary light. And be quiet!" They went, through connecting passages. The noise of Dio's party grew ominously loud. Abruptly, the leader swore. "Caron or no Caron, he's gone. And we'd better go, too." He turned off, down a different tunnel, and Gray heaved a sigh of relief, remembering the body he'd left in the open. For a time the noise of their pursuers grew remote. And then, suddenly, there was an echoing clamor of footsteps, and the glare of torches on the wall of a cross-passage ahead. Voices came to Gray, distorted by the rock vaults. "I'm sure I heard them, just then." It was Jill's voice. "Yeah." That was Dio. "The trouble is, where?" The footsteps halted. Then, "Let's try this passage. We don't want to get too far into this maze." Caron's leader blasphemed softly and dodged into a side tunnel. The man next to Gray stumbled and cried out with pain as he struck the wall, and a shout rose behind them. The leader broke into a run, twisting, turning, diving into the maze of smaller tunnels. The sounds of pursuit faded, were lost in the tomblike silence of the caves. One of the men laughed. "We sure lost 'em!" "Yeah," said the leader. "We lost 'em, all right." Gray caught the note of panic in his voice. "We lost the markers, too." "You mean...?" "Yeah. Turning off like that did it. Unless we can find that marked tunnel, we're sunk!" Gray, silent in the shadows, laughed a bitter, ironic laugh. * * * * * They went on, stumbling down endless black halls, losing all track of branching corridors, straining to catch the first glint of saving light. Once or twice they caught the echoes of Dio's party, and knew that they, too, were lost and wandering. Then, quite suddenly, they came out into a vast gallery, running like a subway tube straight to left and right. A wind tore down it, hot as a draught from the burning gates of Hell. It was a moment before anyone grasped the significance of that wind. Then someone shouted, "We're saved! All we have to do is walk against it!" They turned left, almost running in the teeth of that searing blast. And Gray began to notice a peculiar thing. The air was charged with electricity. His clothing stiffened and crackled. His hair crawled on his head. He could see the faint discharges of sparks from his companions. Whether it was the effect of the charged air, or the reaction from the nervous strain of the past hours, Mel Gray began to be afraid. Weary to exhaustion, they struggled on against the burning wind. And then they blundered out into a cave, huge as a cathedral, lighted by a queer, uncertain bluish light. Gray caught the sharp smell of ozone. His whole body was tingling with electric tension. The bluish light seemed to be in indeterminate lumps scattered over the rocky floor. The rush of the wind under that tremendous vault was terrifying.