Last in Herbert's Dune trilogy, this ponderously realigns the surviving family of the departed (or not so departed) messiah Muad'Dib, Paul Atreides. Paul's sister Alia, one of the ""pre-born"" who carry the living memories of the entire Atreides ancestry back to Agamemnon, becomes possessed by the spirit of a long-dead forebear and embarks on a ruinous power game which threatens both the ecological basis of Dune's crucial spice trade and the lives of Paul's children, the nine-year-old twins Ghanima and Leto. Among the increasingly crazed intrigues of Alia and the risky intervention of Paul's mother, the twins struggle to master their perilous ancestral memories and more-than-adult mental powers. At stake are the precious ecology and ethos of Dune itself, with terrible consequences for the scattered planets of the Imperium. It's sometimes gripping, but dreadfully overwritten (""the parched glissando of moonglow"") and self-important beyond description, with at least two great thoughts to a page, and sometimes three or four. Still, that's just what seems to attract the post-born true believers.