Frank Herbert's Children of Dune

Under Paul "Muad'Dib" Atreides' rule as Emperor, the planet Arrakis has enjoyed a renaissance. However, the revolution that Muad'dib inspired has transformed into a brutal jihad that has plunged all of humanity into a bitter, neverending cycle of interstellar war. Now a conspiracy on Arrakis threatens to rob Muad'Dib of his throne and his life. The future of all of humanity might well rest in the hands of Muad'dib's young, vulnerable heirs - Leto II and his sister, Ghanima. Idealistic young Leto, however, fiercely resists his destiny as a force for sweeping changes, both on Arrakis and in the universe at large. Unfortunately, the time for Leto to take action is drawing near, and friends and enemies are difficult to tell apart on Arrakis, where the only thing more precious than water is the Spice, a substance found only on Arrakis that makes possible interstellar space travel; extends life; and enables people who ingest it to have clairvoyant visions of distant places and of the future. With the rule of Arrakis and the freedom of all humanity hanging in the balance, Leto must risk sacrificing his own humanity in order to save those who would see him destroyed.