A landslide started near the rim, and earth rumbled forward down the side of the depression, disappearing as it touched the outside of the energy-shell that was Carroll's reflector. The rim of trees that supported the energizing ring fell into the widening inverted funnel but its job was over. The mirror was stable, held by the energy contained in the perfect sphere on the column near its edge. The rumbling stopped as stability came. The roar, all of it sheer physical sound from tortured earth, died and left a hollow vacancy in comparison. Then Carroll took a small set of levers and manipulated them like a man flying a drone airplane. The sphere of energy left the column and was driven over the gaping maw of the mighty reflector. Down it dropped until it was at the exact focus of the paraboloid. There it compressed to almost a point. "This," said Carroll, "is it!" He reached for the master switch just as a flashing bolt of coruscating energy dazzled across the room, searing his arm. "King!" screamed Rhinegallis. "Don't!" CHAPTER XIII _Last Chance_ Through the door swarmed Kingallis and four of his henchmen. They paused to get their bearing and then they plunged forward, shouting. Rhine made ineffective gestures against them--pure instinct, for her senses were shocked by their abrupt appearance. Carroll cursed. His sense of timing told him that there was no second to waste, yet his right arm hung useless and he was reeling weakly from the shock. They did not fire again as they came swarming across the floor, but their interception of his move was as effective. Kingallis, with an angry shout, caught Carroll and hurled him away from the panel. [Illustration: Kingallis caught Carroll and hurled him away from the panel.] Two of the others took Rhine by the arms and drew her back out of the way. "Now!" snarled Kingallis, with sheer animal tones in his voice. "We'll see about this!" He waved the other two aside and back and then stepped forward to slap Carroll across the face. The blow, meant as an insult strong enough to arouse fighting instinct, was strong enough to stagger Carroll. "Weakling," scoffed Kingallis. He back-handed the staggering physicist again and again, driving Carroll against the far wall of the laboratory. "Come on and fight," sneered Kingallis. Rhine shrieked in mad anger. "Fight?" she shrilled, "after you've shot him?" Kingallis kicked Carroll in the abdomen. "Coward!" screamed Rhinegallis. With a superhuman strength born of sheer madness, Rhine hurled herself out of the hands of her captors and raced across the floor. Her fingernails came down across her brother's face drawing a torrent of blood from torn eyelids. At the same time she kneed him in the stomach. Her blow was more effective than Kingallis's had been on Carroll. He stumbled back writhing in pain.