What had happened? Where was he? What was this thing that pushed him, stumbling, along through the dark? With all his tumultuous questioning he knew only one thing definitely: that it would be of no use to struggle. He was as helpless as any trapped animal. He was inside the earth, of course; he had fallen he had no least idea how far; and, in some strange manner, this long-armed thing had supported him and eased him gently down. But what it meant or what lay ahead were matters too obscure for him to try to see clearly. He held his hands protectingly before him while the talons gripping into his shoulder hurried him along. He stumbled awkwardly as his foot struck an obstruction. He would have fallen but for the grip that held him erect. For that creature, whatever it was, the darkness held no uncertainty. He moved swiftly. His shrill shriek and the jerk of his arm both gave evidence of his astonishment that his captive should walk so blunderingly. Then it seemed that he must have comprehended Rawson's blindness. A green line of light passed close behind Dean's head. It was cold--there was no radiant warmth--but, when it struck the face of a wall of stone some twenty feet away, the solid rock turned instantly to a mass of glowing yellow-red. The cold green ray swung back and forth, leaving a path of radiant rock behind it wherever it touched. And the rock was hot! Once the green light held more than an instant in one place, and the rock softened at its touch, then splashed and trickled down to make a fiery pool. * * * * * Abruptly Rawson was able to see his surroundings. Also, he knew the source of the red glow that had seemed like volcanic fires. There had been others like his captor; they had been down below, and had played their flames upon the rocks deep in the volcano. It was thus that they made light. With equal suddenness, and with terrible clearness, Dean found the answer to one of his questions. He wrenched himself about to stare behind him at the creature that held him in its grip. And, for the first time, the wild experience became something more than an unbelievable nightmare; in that one horrifying instant he knew it was true. Only a few minutes before, he had been walking across the cindery sand of the crater top, walking under the stars and the dark desert sky--Dean Rawson, mining engineer, in a sane, believable world. And now...! He squinted his eyes in the dim light to see more plainly the beastly figure, more horrible for being so nearly human. He had seen them briefly up above; the closer view of this one specimen of a strange race was no more pleasing. For now he saw clearly the cruelty in the face. It was there unmistakably, even though the face itself, under less threatening circumstances, might have been a ludicrous caricature of a man's.