Children of Dune recap

Nine years after Paul's disappearance, his twin children, Leto II and Ghanima, are the pre-born heirs of the empire, guarded on Arrakis while their aunt Alia rules as Regent. Alia has lost her inner struggle and become an Abomination, possessed by the ego of her ancestor, the tyrannical Baron Harkonnen, and her rule grows cruel and erratic. A blind Preacher wanders in from the desert denouncing the corrupt religion of Muad'Dib; he is Paul himself, still alive. House Corrino, exiled on Salusa Secundus, plots the twins' murder to reclaim the throne, sending genetically tampered tigers to kill them. Leto and Ghanima, sharing prescient visions, foresee a terrible Golden Path that alone can save humanity from extinction, and Leto resolves to take it. Faking his own death, Leto ventures into the desert and bonds his body with sandtrout, gaining superhuman strength and near-immortality as he begins a transformation toward becoming a human-sandworm hybrid. Paul the Preacher is killed by a mob in the city. Leto returns, overpowers all opposition, and forces Alia to confront the monster she has become; she takes her own life. Leto seizes the throne, betroths Ghanima to the Corrino heir Farad'n to bind the rival house, and commits himself to a reign of millennia, sacrificing his own humanity to steer the species along the Golden Path his father dared not walk.

Previously in the Dune series: Paul Atreides, heir to a noble house destroyed by treachery on the desert planet Arrakis, fled into the deep desert with his Bene Gesserit mother, Lady Jessica. Among the native Fremen he became the messiah Muad'Dib, awakened to prescient vision by the planet's spice, and led a desert uprising that toppled the emperor and won Paul the imperial throne. His birth-conscious sister, Alia, and his beloved Fremen partner, Chani, stood with him, though he wed the old emperor's daughter Irulan for politics alone. Paul's rule unleashed a holy war that slaughtered billions in his name. Twelve years later, in Dune Messiah, rival powers conspired against him. They blinded him with a forbidden weapon, and though his foresight let him carry on, their schemes cost him dearly: Chani died giving birth to twins, Leto and Ghanima, both born with the ancestral awareness of the pre-born. Paul foiled the plot but, at last wholly blind, chose the Fremen death of walking alone into the desert, leaving his infant heirs behind. His sister Alia took up the regency, ruling the empire alongside the resurrected swordmaster Duncan Idaho, whom the plotters had returned to Paul as a ghola and who had broken his conditioning to remain loyal. Now the empire is governed in the name of two prescient children, the desert planet slowly greens under Muad'Dib's ecological dream, and the machinery of religion and power built around a dead messiah grinds on.

The book ends with the rise of a new and stranger ruler. Leto II, having secretly left his sister Ghanima and slipped into the desert, merges his skin with a living sheath of sandtrout, gaining tremendous strength, speed, and resistance to harm at the price of his ordinary human future. He embraces the Golden Path, a design of prescience meant to guarantee humanity's long-term survival even at monstrous personal cost. His aunt Alia, wholly possessed by the inner ego of the old Baron Harkonnen, spirals into tyranny; when Leto returns and forces her to face what she has become, she throws herself to her death. The mysterious Preacher, revealed as Paul Atreides returned from the desert, is struck down and killed by a crowd in the city, his warnings against the religion of Muad'Dib unheeded. Leto overcomes the Corrino assassination plot and takes power as the new emperor. He pardons and binds the young Corrino heir Farad'n by betrothing him to Ghanima, making the rival house serve the Atreides line. Lady Jessica reconciles herself to what her grandson has chosen. Leto sets the empire on the path of his long metamorphosis into a god-emperor, accepting that he will rule for thousands of years as something no longer fully human in order to save mankind from itself.