He walked about the great bowl, watching the lights flicker behind the plastic wall, seeing the sluggish movements of the creatures who sucked the life forces from the liquid bubbling so gently. Then with a calm viciousness that surprised even himself, he methodically crushed each of the pinkish monsters to death. And with the death of the last monster, the first of the Gharrians in the hall attacked the door. Great sledging blows smashed at the plastic, each blow driving bulges where no man could have scratched the surface. Kimball Trent stared thoughtfully at the bulging panel, his mind working clearly for the first time in minutes. There was no fear in him now, no blazing hate, only the crystal brightness of logic in his mind. He looked about the room, then beckoned for Lura to come to his side. She came trustingly, staring into his eyes, and he knew then his future was yet to come. He grinned, kissed her gently. "You will do as I say. Go to the Reader and tell him to read about sound waves. Tell him that the Gharrians can be killed with supersonic waves of sound; that that is the _only_ way that they can be killed while in their armor. Do you understand?" "I understand," Lura said quietly. "But I do not leave." The door shattered inward, hanging on a single hinge, and through the opening came the invulnerable Gharrians, moving slowly toward the unarmed Earthman and girl. Kimball Trent swung the girl behind him, retreated, wondering if the mad scheme he had would possibly work. And even as he thought, his hand reached out, ripped loose the cables from one of the motors that fed the current to the life-trap bowl. He raced to the second, tore the cables free, winced, as the motor sang a shriller song, power mounting now that it no longer fed the bowl. He tore the third bunch of cables free, then shielded Lura with his body, as the motors began to race with incredible speed, their screams mounting higher and higher. Still the Gharrians came forward, moving with an implacable deadliness that nothing could stop apparently, their concussors dangling from their waists. They would use their strength here, for concussion would wreck the life bowl, and they had no reason to fear the puny strengths of the couple they faced. The screams of the motors were like knife blades now, biting into every nerve, wrenching agony from their brains. Trent and Lura gasped from the pain, pressed farther back around the great transparent bowl, striving desperately to evade that last moment when the Masters would reach them. And then the shrill screams of the motor eased, were gone, vibrations scaling past the audible, going into a supersonic range that their ears could not catch. The first Gharrian lifted a mailed arm--and died. * * * * * He died rather horribly, beating insanely at his companion and the plastic wall. Then he was dead, and was but a toppling metal hulk that smashed to the floor.