First of a five-book series from the author of Xenocide, the Alvin Maker tales, etc. Planet Harmony, settled 40 million years ago following the destruction of Earth, is overseen by the Oversoul, an intelligent computer able to communicate telepathically with certain of the inhabitants. Set up to prevent war and ensure the colony's survival, the Oversoul is now breaking down, and for repairs must journey to Earth (where, the Oversoul theorizes, a new civilization surely will have arisen by now). Needing help from Harmony, the Oversoul first contacts young student Nafai of the matriarchal city Basilica, hoping to persuade him and others of his family to secure the Index--an ancient machine that will enable the Oversoul to talk directly with everyone. A major complication is that as the Oversoul decays, the mental blocks it implanted in Harmony's people eons ago to prevent war are also breaking down; and soon the women of Basilica find themselves trapped in a power struggle between two hostile male armies. Where Card focuses on children--as he often does here--he writes fluently and persuasively. Elsewhere, his adult characters and motivations are much less appealing. Neither is the ancient-computer backdrop, with its far-fetched Earth connection, particularly convincing. All in all, an uneven and irritatingly inconclusive starter.