Five hundred years into the future, mankind has left Earth. All the people moved to a new large star system. The system is controlled by the Alliance. Away from the "core planets" people like the crew of the cargo ship "Serenity" can make a living if they stay away from Alliance ships and the Reavers - space-faring cannibals who raid the planets of "the Rim." One of the Alliance's projects is the creation of a group of warriors with mental powers. The star of this project is teenager River Tam. After her older brother Simon rescues her, the Alliance Parliament sends "The Operative", a man with no name, rank or official existence after them.