Robbed of the powerful object she needed to save her mother, time traveler Etta Spencer is stranded far from home and the privateer she loves before resolving to destroy the astrolabe, a mission that is challenged by a shattering revelation.

After crash-landing on an uncharted planet, astronaut Taylor (Charlton Heston) finds himself trapped in a savage world where talking apes dominate the human race. Soon, Taylor's life depends on the kindness of the chimpanzee scientists Cornelius (Roddy McDowall) and Zira (Kim Hunter) and his escape to the Forbidden Zone, where he uncovers an earth-shattering secret that may hold the key to his own destiny.