Searing near-future polemic on overpopulation that unaccountably fades into clichÃ‰, from the author of It Came from Schenectady (1984). The overcrowded early 21st century is an era of strict birth control; so when ""illegal"" seven-year-old Thomas Windom is discovered by the authorities, he's sent to the ""outcasters"" orphanage. Here, an utterly brutal and degrading system prevails (thanks to propaganda, the guards are taught to hate and despise the illegals), where beatings, rapes, and torture are routine. The kids retaliate, forming a club that metes out reprisals for the guards' worst excesses. After one particularly nasty episode, Thomas retreats into an autistic state. Six years later, Thomas re-emerges. Thirsty for knowledge, he learns that the world is run by supercomputer MAC III (cf. Philip K. Dick, Isaac Asimov et al.). MAC is planning a humane war in order to reduce the surplus population. Burning with the need to know why MAC acts as it does, Thomas escapes the camp. But MAC keeps tabs on everyone, and eventually MAC agents catch him--and offer him an implanted computer link plus the chance to serve MAC directly. Numbly, Thomas accepts and becomes an assassin (he even eliminates some friends and former orphanagemates). Finally he comes to accept that, while MAC is so advanced that no human can understand its workings, MAC is benevolent and the war is necessary--so he pushes the button that triggers doomsday. The orphanage scenes are horrifying and gripping if somewhat overdone: Longyear is at his best when writing about adolescents and teen-agers. Unfortunately the last third, where Thomas ceases to struggle and accepts MAC, is a tame surrender by comparison. Familiar material, then, though in an arresting package, and about half satisfying overall.