In the 26th century, humanity has left an overpopulated Earth to colonize a new solar system. The central planets formed the Alliance and won a war against the outer planet Independentsâthose refusing to join the Alliance. River Tam (Summer Glau) is coercively conditioned by Alliance scientists into a psychic assassin. She is rescued by her brother Simon (Sean Maher). During her training, River inadvertently read the minds of several officers and learned top government secrets. Consequently, a top Alliance agent known only as the Operative (Chiwetel Ejiofor) is tasked with recapturing her.