They were heading for Tau Ceti, to a paradise planet that could become a new home for humanity. But after covering three quarters of the way, their ship—a giant ark—broke down. The engines failed, controlled by a computer made on the basis of the human psyche. The human psyche simply could not withstand the trial of space. And then the future colonists had no other choice but, under terrible time pressure, to create a new Artificial Intelligence to control the ship...