Welkir remained silent, glaring at them. He turned and whispered to the Chief Commoner. The Chief Commoner whispered to Slubil. The executioner nodded grimly and took a short-axe from his belt thong. He stepped through the entrance, his left foot striking the zero-tile. He peered at Big Joe and saw that the monster remained motionless. He grinned at the ones behind him, then snarled in Asir's direction. "Your sentence has been changed, thief." "Don't try to cross, Slubil!" Asir barked. Slubil spat, brandished the axe, and stalked forward. Big Joe came up like a resurrection of fury, and his bellow was explosive in the vaults. Slubil froze, then stupidly drew back his axe. Asir gasped as the talons closed. He turned away quickly. Slubil's scream was cut off abruptly by a ripping sound, then a series of dull cracks and snaps. The girl shrieked and closed her eyes. There were two distinct thuds as Big Joe tossed Slubil aside. The priests and the townspeople--all except Welkir--had fled from the corridor and up the stairway. Welkir was on his knees, his hands covering his face. "Mara!" he moaned. "My daughter." "Go back, Father," she called. Dazed, the old man picked himself up weakly and staggered down the corridor toward the stairway. When he passed the place of the first warning voice, the robot moved again--arose slowly and turned toward Asir and Mara who backed quickly away, deeper into the room of strange machines. Big Joe came lumbering slowly after them. Asir looked around for a place to flee, but the monster stopped in the doorway. He spoke again, a mechanical drone like memorised ritual. "_Big Joe is charged with announcing his function for the intelligence of the technologists. His primary function is to prevent the entrance of possibly destructive organisms into the vaults containing the control equipment for the fusion reaction which must periodically renew atmospheric oxygen. His secondary function is to direct the technologists to records containing such information as they may need. His tertiary function is to carry out simple directions given by the technologists if such directions are possible to his limited design._" Asir stared at the lumbering creature and realized for the first time that it was not alive, but only a machine built by the ancients to perform specific tasks. Despite the fresh redness about his hands and jaws, Big Joe was no more guilty of Slubil's death than a grinding mill would be if the squat sadist had climbed into it while the Marsoxen were yoked to the crushing roller. Perhaps the ancients had been unnecessarily brutal in building such a guard--but at least they had built him to _look_ like a destroyer, and to give ample warning to the intruder. Glancing around at the machinery, he vaguely understood the reason for Big Joe. Such metals as these would mean riches for swordmakers and smiths and plunderers of all kinds. * * * * *