Cornelius, Zira and Dr. Milo, three apes from the future, escape from their planet as it is being destroyed and land on 20th century Earth where they are taken to the Los Angeles Zoo for examination. When Zira reveals their ability to speak to a psychologist, the apes are treated as curiosities. However, when the U.S. government begins to believe their story that the Earth will eventually be inherited by apes, it decides to hunt the couple down as an evolutionary threat and tries to prevent the birth of Zira's baby.