"Any indication as to the cause of death?" "None. It apparently came on quite suddenly. We judge that the inhabitants had some warning. At least we do not seem to find enough skeletons for a city of this size, so we estimate that part of the population fled, or tried to." "I see," Thompson repeated tonelessly. He caught a vague impression that something had passed before his eyes, like a darting flicker of light, and he caught, momentarily, a fast rustle in the air, as of souls passing. His mind was on the flight of this race, the mass hegira they had attempted in an effort to escape from some menace. What menace? "What do you think caused it?" Ross shrugged, a gesture eloquent with a lack of knowledge and of understanding. "War--" "No wars were fought on this planet," Neff spoke quickly. "These cities show no evidence of conflict." "Um," Thompson said. The four men were looking uneasily at him. They were waiting for him to make up his mind, to decide on a course of action. Thompson did not like his own thinking. Something--the blood-brother of death--had been here on this planet, that much was certain. The evidence was everywhere. "We will return to the ship," Thompson said. Grant saw them coming, had the lock open for them. His worried face looked out at them. "What gives here?" "We don't know," Thompson answered. The cat, Buster, pushed forward between Grant's legs, took a long leap at Thompson's chest, made a twenty-claw safe landing there. "Hi, old fellow, were you worried about me?" They passed through the lock. "Take her up," Thompson said. "We need a little time to think about this enigma. Maybe we can think better when we're not so close to it." At his words, relief showed on the faces of the men. "Maybe sometime soon we'll be heading for home?" Kurkil spoke, grinning hopefully. "You can be certain of that," Thompson said. * * * * * The ship lifted, hung miles high in the air above the silent planet. The group considered the problem. "I vote to make a complete investigation," Grant said. He was full of eager enthusiasm. "There was a race here. Something happened to it. We've got to find out what happened because--" He got no further. Slowly the enthusiasm went from his face. "No, that's not possible," he ended. "There's no danger of the virus that destroyed this race crossing space to Sol Cluster," Kurkil spoke. "The distance is too great." "The distance wasn't too great for us to cross it," Fortune spoke. "Please," Thompson interrupted. "We can't use logic on this situation until we have adequate data. The only data we have--" His voice trailed off into silence as his memory presented him with a facsimile of that data--silent, deserted cities, a world going back to vegetation, three skeletons in front of a shrine.