His hand swept into the open front of his shirt and came out again with one of the hand guns Zurk--or Guyard--had made in the secret furnace. In one swift motion, he leveled the gun at Zuldi's huge chest and squeezed the trigger. The crash of the explosion jarred against Zurk's ears with a shattering force that drove some of the blackness from his brain. He saw immediately that the charge had not reached its intended mark. One of the other creatures, at sight of the gun, had leaped suddenly forward--to receive the heavy slug in his own chest. The bullet did not stop him. His momentum carried his dead body forward to crash into Bob, to knock the gun from his hand and to send him spinning and stumbling backward. Zuldi laughed, and drew his voltage gun. During that split second, a thousand other vibrations smashed into Zurk's hot brain. He heard bedlam break loose in the streets below. The Earthians were fighting! Mingled with the crash of the hand guns and the slithering vibrations of the voltage weapons were cries, groans, shouts and curses. And over it all came the sudden, high-pitched whine of the black ship's radio, a whine to the far side of the moon for help. Soon there would be other black ships. Marene was standing there looking at him, her eyes staring into his own, pleading with him! Then she turned and made a dash for the long-snouted gun upon the table, only to be dragged away from it by two of the monsters. Zurk knew that the last, insane episode had come. This was to be the last of the Earthians! And if he were ever going to come to their aid, he must do it now. * * * * * He threw all the power of his giant frame into the will to stand, into the will to rise up and to slay these evil creatures about him. He tried to ignore the stabbing pain at his back, tried to believe it did not exist. He hurled forth his energy in wave after wave until the flame became a consuming thing that ate deep within him and filled his brain with the shadows of dark despair. Through that creeping blackness, he saw Bob Simms frantically try to evade the sweep of Zuldi's weapon. He felt the young man stumble over one of his helpless, steel feet, felt him stagger against his metal knee and fall. And at almost the same instant the blast from Zuldi's voltage gun went crashing through the room. Zurk saw the streak of the charge as it passed just above the fallen youth and felt the full, deadly shock of it strike squarely into his own huge chest of steel with a force that quaked the whole of his giant frame. Then came deep silence. It seemed that all time had suddenly stopped. Zuldi and the other creatures were standing there staring at him, their bulging eyes terror-stricken. The vibration of Marene's sudden cry swept against his ears. "_Zurk! You are free!_"