"_This_," said the toneless voice: "_Destroy me. Leave no slightest trace. I live in hell, and have no way to move.... There are old memories ... things that once were dear ... Earth ... my homes ... my lives there.... Eliot Leithgow, destroy me. But promise, on your honor as a Master Scientist, never to let a single word regarding my fate reach those on Earth who knew me, loved me...._" Leithgow looked at the Hawk. The adventurer nodded. "I'll use the heat-ray," he said, with pity. He ran and picked it up. But he had taken only one step in return when the second hinge of the yielding door wrenched free. An ear-piercing screech rent the bedlam--and the door fell, half twisting, to lie in the doorway. As if by a signal the crashing at the other doors stopped. In an extraordinary silence a mob of gray-smocked bodies pressed forward. Orange streaks laced the dim laboratory. The Hawk shouted, "Up, Eliot! For God's sake, up!" as, with deadly effect, he poured his two ray-guns at the advancing men. For a second, shaken by the terrible barrage, they fell back, leaving several sprawled bodies on the floor; but they came right back again. Leithgow got safely to the top of the pile and was snatched out to temporary safety. Frantically Friday called down to his master; he seemed on the point of jumping down into the fight himself. But Hawk Carse had been party to a promise. He was behind the structure of furniture under the hole he had made in the ceiling. With one gun he spat death at the coolies, while the other he emptied at the case of brains. Two stabbing streams of orange angled from him, one telling with awful effect on the men only two score feet away, and the other absolutely useless. All over the still-glowing case it spat its hits, but the glasslike substance resisted it completely, and remained unscathed. Carse swore harshly. He hurled one empty gun at the case, turned with a last salvo of shots at the coolies, and then was up on the pile and leaping for Friday's hands. They caught and gripped his, swung him once--twice--and hauled him swiftly out. But as the Hawk disappeared he shouted down the case: "I'll be back!" CHAPTER XIII _The Final Mystery_ On the roof, Carse quickly scanned their situation. They were standing on the hub of the four-winged building. Far to the left was one set of the dome's great and small port-locks; exactly opposite was the other. Near the left hand ports; a little "north," lay the _Scorpion_. The whole area enclosed was a flat plain of gray soil.