They're taking over.

Astronauts Pete Burke and Allan Virdon crash on Earth in the far future and are captured by the apes. The men befriend a chimp named Galen who helps them to escape. In the hopes of finding a way to get back to their own time, the astronauts search for a computer in an earthquake-threatened city, with which they will be able to access their flight records. [The first of five telefilms edited from episodes of the 1974 TV series; this film combines the episodes "Escape from Tomorrow" and "The Trap"]