Plot

The world is shocked by the appearance of three talking chimpanzees, who arrived mysteriously in a U.S. spacecraft. They become the toast of society, but one man believes them to be a threat to the human race.

Following the events in "Beneath the Planet of the Apes", Cornelius and Zira flee back through time to 20th Century Los Angeles, where they face fear and persecution similar to what Taylor and Brent suffered in the future, and discover the origins of the stream of events that will shape their world.—Marg Baskin <marg@asd.raytheon.ca>

Cornelius and Zira, the simian ape couple from the first two ape films, flee from their doomed planet (after the events in Beneath...) in the same spaceship used by Taylor in the first film, and travel back through the same space/time porthole and land on late 20th Century Earth where they are received with fascination and fear from the people they meet.—Michael Zink

The third chapter of the Apes saga. Two intelligent simians from the future, Cornelius and Zira, travel to present-day Earth. They become instant sensations, wined and dined and treated like celebrities -- until a high-level plot forces them to run for their lives.—Robert Lynch <docrlynch@yahoo.com>

Prior to Earth's destruction, the chimpanzees Cornelius, Zira and Dr. Milo salvage and repair Taylor's spaceship and escape the planet. The shock wave of Earth's destruction sends the ship through a time warp that brings the apes to 1973 Earth. Most specifically, the Pacific coast of the United States.

The apes are transported to the Los Angeles Zoo, under the observation of two friendly scientists, Dr. Stephanie Branton and Dr. Lewis Dixon. During their stay there, Dr. Milo is killed by a zoo gorilla.

A Presidential Commission is formed to investigate the return of Taylor's spaceship and its inhabitants. During their interrogation, Cornelius and Zira deny knowing Taylor. They reveal, however, that they came from the future and escaped Earth when a war broke out. They are welcomed as guests of the government. The apes secretly explain to Stephanie and Lewis how humans are treated in the future, and tell them about Earth's destruction. The scientists are shocked but still sympathetic, and advise the couple to keep this information secret until they can gauge the potential reaction of their hosts.

Lavished with gifts and media attention, the apes become celebrities. They come to the attention of the President's Science Advisor Dr. Otto Hasslein, who discovers Zira is pregnant. Fearing for the future of the human race, Hasslein insists that he simply wants to know how apes became dominant over men. Cornelius reveals that the human race will cause its own downfall and that Earth's destruction is caused by a weapon made by humans. Zira explains that the gorillas started the war, but the chimpanzees had nothing to do with it. Hasslein suspects that the apes are not telling the whole truth.

During the original hearing, Zira accidentally reveals that she used to dissect humans. Hasslein orders Lewis to administer a truth serum to her while Cornelius is confined elsewhere. As a result of the serum, Hasslein learns details about Zira's experimentation on humans along with her knowledge of Taylor.

Zira joins Cornelius in confinement while Hasslein takes his findings to the President, who reluctantly abides by the council's ruling to have her pregnancy be terminated and that both apes be sterilized. In their chambers, Zira and Cornelius fear for their lives. When an orderly arrives to offer the apes food, his jokes about their future child make Cornelius lose his temper. He knocks the orderly to the floor, before escaping with Zira. They assume the orderly is merely knocked out, but he is actually dead. Hasslein uses the tragedy in support of his claim that the apes are a threat. He calls for their execution, but is ordered by the President to bring them in alive, unwilling to endorse capital punishment until due process has been served.

Branton and Dixon help the apes escape, taking them to a circus run by Señor Armando, where an ape named Heloise has just given birth. Zira gives birth to a son and names him Milo, in honor of their deceased friend. Knowing that Zira's labor was imminent, Hasslein orders a search of all circuses and zoos, and Armando insists the apes leave for their safety. Lewis arranges for the apes to hide out in the Los Angeles harbor's shipyard for a while. He gives Cornelius a pistol as the couple does not want to be taken alive.

Tracking the apes to the shipping yard, Hasslein mortally wounds Zira and kills the infant she is holding. Cornelius shoots down Hasslein, and then dies at the hands of a sniper. Zira tosses the dead baby over the side and crawls to die with her husband, witnessed by a grieving Lewis and Stephanie.

It is revealed that Zira switched babies with Heloise before leaving the circus. Armando is aware of this and prepares to leave for Florida. Baby Milo then begins to talk.