the Planet of the Apes is a 1973 science fiction film and is the fifth and final entry in the Planet of the Apes series. It was directed by J. Lee Thompson. Considered by critics to be the weakest of all the sequels; the film's budget was also the lowest.
This synopsis is based on the extended version of the film released to syndicated TV in the late '70s and more recently on DVD and Blu-Ray.
Set in flashback to the turn of the 21st century, and told by the Great Lawgiver, this sequel focuses on the ape leader, Caesar (Roddy McDowall), almost a decade after he led the ape revolution in the previous film, Conquest of the Planet of the Apes. In this post-nuclear war society, Caesar tries to cultivate peace between his simian peers and the surviving remains of humanity. Gorilla leader Aldo (Claude Akins), however, wants nothing to do with this; therefore he plots Caesar's overthrow and doom. Caesar is now married to Lisa (Natalie Trundy), the female ape of the previous film, and they have a son, named Cornelius (Bobby Porter) in honor of Caesar's father. Caesar regrets having never known his parents until his human assistant MacDonald (Austin Stoker) informs him that by viewing taped archives of his parents, he can learn of the future. Caesar learns the archives are in the Forbidden City, once the city where Caesar was enslaved in, and is now nuclear ruins. After obtaining the specific weapons from an armory run by Mandemus (Lew Ayres), Caesar travels with MacDonald and Virgil (Paul Williams) to the Forbidden City and sneaks in to find the record archives. However, there are radiation-scarred humans still living in the Forbidden City, now under the command of Governor Kolp (Severn Darden). Caesar and his party view the recordings of Cornelius and Zira and learn of the future of the world, but barely have enough time to study the tapes before they must escape or risk capture and death.
Cornelius assembles a meeting with the citizens to report his discoveries at the Forbidden City. Aldo objects to Caesar even when some humans show up in an Ape Council.
The scout group sent by Governor Kolp return and tell them about the Ape City. Kolp considers this clandestine entrance by Caesar an act of espionage while his subordinate Méndez (Paul Stevens) says that they did nothing wrong and should be allowed to go in peace. Governor Kolp then declares war on Ape City, mustering the humans from the Forbidden City to destroy the ape society once and for all.
Aldo is furious over the fact that Caesar wants to co-exist peacefully with humans and plots a military coup in order to install himself as the leader of Ape City. Cornelius (while climbing a tree) overhears this, but is spotted by Aldo who hacks at the branch with his sword causing Cornelius to suffer serious injuries and remain bedridden. After one of the scouts is wounded by Governor Kolp, Aldo takes action into his own hands and orders all humans rounded into the corral. Then, Aldo leads the gorillas to loot Mandemus' armory for its weapons.
Caesar is devastated by his son's death after learning of Aldo's actions by Virgil. He leaves the side of his now-dead son when he learns Kolp's ragtag force is attacking Ape City.
The mutants attack Ape City and initially succeed, forcing Caesar to order the defenders to fall back. When Kolp finds Caesar, he taunts him, saying the apes would once again be humanity's slaves, and is about to shoot him. But then Lisa cries out, and Kolp is distracted. Caesar shouts NOW, FIGHT LIKE APES!!!, and the fallen apes all around them, who were feigning death (clearly on Caesar's orders), launch a counter-attack that captures most of the mutants and drives Kolp into retreat. Kolp and his remaining forces are killed by Aldo and his troops. After the battle, Aldo wants to kill the humans in the pen, but Caesar shields them. Aldo declares that Caesar should be killed if he shields the humans. But before he can carry this out, it is revealed that Cornelius' death was not due to an accident, but Aldo's malevolence. The ape community concludes that the society's sacred law ("ape must never kill ape") has been broken. As the community repeats "ape has killed ape", an infuriated Caesar attacks Aldo, and their fight results in Aldo's death. Caesar then goes to free the humans, but they refuse to leave the pen unless things change. MacDonald insists that freedom is meaningless without being treated as equals. Caesar then realizes the apes are just as despicable as the former slave-owners if they treat the humans as second class citizens. The apes and humans then decide to coexist with one another and begin to make a new society.
The wizened orangutan at the beginning of the film (the Great Lawgiver played by John Huston), finishes the narration begun in the prologue (which takes place over 600 years later) to a group of young humans and apes. Instead of humanity falling and apes rising to take their place, the two species have continued to coexist. When asked by a human child what the future will hold, the Lawgiver states that only the dead know about the future. It then zooms over to a statue of Caesar and shows water coming from the left eye when there's a face shot.
However, screenwiter Paul Dehn stated that the last shot of the film showing a tear on the statue of Caesar was to let the audience know that Caesar's plans ultimately failed. It could also be a clue to mankind's eventual fall as seen in the first two films. The ultimate message of the film is that we write the future with our own behavior, and how we treat those around us.