In the year 2009, a meteor shower above Earth claims the life of Americanastronaut Jeff Hale. He awakens inside a jade-green bubble beneath the surface of a body of water filled with other such bubbles. A mysterious cloaked figure pierces his bubble with a staff pressing it against his forehead, forcefully filling his mind with images to come. Dazed and in pain, he soon finds himself crawling nude onto a beach littered with metal canisters containing unisex clothing. Soon dozens of people from different lands and historical eras emerge from the water, also nude, and distribute the canisters. All understand each other's language, except a lone Neanderthal man, who lacks the capacity for speech. Hale learns that the "known world" is the bank of a massive river. Anyone who has ever lived on Earth at any time in history is qualified to start life anew on Riverworld, reborn in his or her prime of life. Other cloaked figures are seen fleetingly, but their purpose is unknown. Food is provided, and the climate is clement. The need for shelter is easily provided by available resources and simple manual labor. Hale meets and makes close friends with some of his fellow castaways, all of them from different time periods: Alice Liddell Hargreaves ; Mali, a former slave of the pre-Civil War era; and Lev Ruach, a Jewish victim of the Nazi Holocaust. The Neanderthal among the castaways is later killed by a man introducing himself as Lucius Domitus Ahenobarbus, a citizen of Ancient Rome. When Hale begins to argue with Lucius about the latter's ethics, Lucius attacks him for the leadership; but their fight is interrupted by slavers under the rulership of one Valdemar, who has erected his own empire and plans to expand it. While in captivity, Hale and the others are joined by two more prisoners: Monat, an extraterrestrial who died – along with the rest of mankind – in a cataclysm in the year 2039; and a young girl named Gwenafra, the only human being in Riverworld reborn as a child. During the night, Hale is freed by the hooded stranger he saw upon his reawakening in Riverworld, hides from Valdemar's men, and follows his fellow resurrectees to Valdemar's fortress. While freeing his mates, he witnesses Valdemar holding gladiatorial games, in which the despot is challenged and killed by Lucius, who identifies himself as the historical Nero and subsequently takes over Valdemar's forces. Monat leads his fellow captives to a community of fugitives led by Samuel Clemens, who has built a riverboat christened the Go For Broke, augmented by Monat's technological expertise, to explore the river. Nero intends to use Clemens' riverboat to extend his dominion downriver. With the aid of a traitor in Sam's ranks, he invades the fugitives' camp, imprisons Hale and his comrades, and forces Clemens to show him how to operate it. Hale and the others overcome Nero and his men, reclaiming the riverboat, and Hale personally kills Nero in combat. Following their liberation, the band travel upstream to explore the Riverworld. Sam gives command to Hale, but remains pilot. Nero is subsequently shown resurrected in a new body somewhere else underneath the river.
Differences from the Riverworld books
A number of liberties are taken in the film with regards to the source material. The original hero and villain are replaced by other characters, the timeline of events is compressed, and the nature of the resurrection process and food and clothing production are altered. Instead of a single meteor of iron, a "valley of meteors" with a constant stream of small falling objects provides the metals used by the characters. The Riverboat is powered by fusion rather than being recharged by Grailstones. The character Loghu is apparently replaced with another female warrior named Mali, and the alien Monat is radically different in appearance and behavior from that described in the books.
