 En route to Alpha Centuri at the start of the 1980s, a spaceship is somehow thrown forwards in time, and crashlands on a strange planet. One of the astronauts is dead, but the other two learn that it is 21 March 3085, they re on Earth, and the world is ruled by apes. Upon their capture by the ruthless General Urko, Dr Zaius s new assistant (Galen) discovers that there were other human astronaut visitors, whose very existence was kept secret. He and Zaius want to study them, but when Urko plots to have them shot for escaping, Galen accidentally kills a guard, and becomes a fugitive. Together, they search for the other intelligent humans they think have survived, plus a way to return home.