The wavering light had shown many passages through the rock. Glazed, all of them. Either they had been blown through molten rock which had then solidified to give the glassy surfaces, or else--and this seemed more likely--the flame-throwers had done it. Rawson, scanning the labyrinth for some recognizable strata, had a quick vision of these caverns being cut out and enlarged, and of their walls melted just as they were being melted now--melted and hardened again innumerable times by succeeding generations of red and yellow-skinned men. Yes, they were men. He admitted this while he walked unresistingly between two of the giants. Another went before them and lighted the way with the green ray of a flame-thrower on the melting rock. These were men--men of a different sort. Evolution, working strange changes underground, had made them half beasts, diggers in the dark, mole-men! They were passing through a long tunnel that went steadily down. Cross passages loomed blackly; ahead of them the leader was throwing his flame upon the walls of a great vault. Rawson had ceased to take note of their movements. What use to remember? He could never escape, never retrace his steps. He tried to whip up a faint flicker of hope at thought of Smithy. Smithy had seen him go, had seen the red mole-men, of course. And he had got away--he must have got away! He would go for help.... But, at that, he groaned inwardly. Smithy would go for help, and then what? He would be laughed out of any sheriff's office; he would be locked up as insane if he persisted. Why should he persist--for that matter, why should he go at all? Smithy would not believe for a single minute that Rawson was still alive. * * * * * His thoughts ended. Webbed hands, wrapped tightly about his arms, were thrusting him forward into a great room. The green flame had been snapped off. One last hot circle on the high wall showed only a dull red. But before it faded, Dean saw dimly the outlines of a tremendous cavern. He saw also that these walls were unglazed, raw; they had never been melted. Below the rough and shattered sides heaps of fragments were piled about the room. Fleetingly he saw the shadowed details; then darkness swallowed even that little he had seen. Clanging metal told of a closing door; a line of red outlined it for an instant to show where it was welded fast. He was a prisoner in a cell whose walls were the living rock. For a long time he stood motionless, while the heavy darkness pressed heavily in upon his swimming senses; he sank slowly to the floor at last. He was numbed, and his mind was as blank as the black nothingness that spread before his staring eyes. In a condition almost of coma, he had no measure or count of the hours that passed. Then a fever of impatience possessed him; his thoughts, springing suddenly to life, were too wildly improbable for any sane mind, were driving him mad. He forced himself to move cautiously.