Astronaut Bill Hudson transmits to Earth from the NASA spacecraft Venturer. On board are crew members Jeff Allen and Judy Franklin. The ship's date is August 6, 1976. Bill explains that they are living proof of Dr. Stanton's "time thrust" theory. Due to the advanced speed of the Venturer, their Earth clock indicates that they have traveled over a century into the future. The craft begins to reel wildly as the Earth clock starts clicking up. The crew blacks out while the ship enters a planet's atmosphere and crashes into a desolate desert region. Meanwhile, General Urko, leader of the gorilla army, is debating before the Supreme Council of Ape City. He demands permission to begin an all-out assault on the humanoids. Cornelius, an animal psychologist, pleads for the council to allow the humanoids to live as subjects of scientific research. The Council decrees that the humans should not be exterminated since they have no language, but they will continue to be hunted, enslaved, domesticated and studied. According to the Book of Simian Prophecy, however, the humanoids must be destroyed if it is ever discovered that they can speak. Bill, Jeff and Judy have escaped their disabled, sinking ship and rafted to shore. Bill's watch reveals the date still to be August 6, but in the year 3979 A.D. With no better plan, they begin trekking across the wasteland. They encounter sudden electrical storms, high-velocity winds, tremors, unexplained flames and ruins. Judy pleads with Bill and Jeff to go on without her, but they refuse. Another mysterious wall of flames consumes their survival packs. After many days, they find green, living plants; water must be nearby. Suddenly, a quake swallows Judy. Frantic, the men move to higher ground in the hopes of spotting her and find a puzzling and frightening sight: ape faces carved into the mountainside. They find a group of primitive humans. They try to speak to them, but the primitives run away. Finally, Bill and Jeff collapse from exhaus

After nearly dying in an attack on the humanoid's caves by General Urko's gorilla army, Jeff is able to hide with Nova and escape capture. Bill is caught and herded into cages with the other captured humans for transport to Ape City. Realizing that Bill can speak, one of the humans motions for him to keep silent as Urko's Jeep comes to a halt near the cages. Bill's shock gives way to terror as he hears Urko comment to his aides that the group of humans will be used for the army's war games. Back in the city, Dr. Zaius promises Cornelius and Zira that they will be allowed to select six specimens for their study from the group of humans Urko is bringing back from the hunt, despite the general's protesting. Outside, the army returns to the cheers of all of Ape City. Meanwhile, Jeff persuades Nova to show him where Bill was taken. After seeing the catch of humans, Zira and Cornelius make their choice of specimens for laboratory study. Bill, whom Zira dubs "Blue Eyes", is among the humans selected. He overhears Zaius tell Urko that if ever humans obtain the power of speech, they must die as a race, so he remains silent for the time being. Zaius plans to send some of the humans to pet stores, some will become laborers, others will go to zoos. Urko, feeling that all humans are worthless, protests and reminds Zaius that someday, when the gorillas are in charge, things will be very different. At the lab, Bill scores highly on all tests much to Zira's delight. Zaius is skeptical, so Zira gives Bill a simple puzzle to assemble. Disturbed, Zaius leaves for a meeting with the Council. Knowing the secret of the planet's evolution, he fears the intelligence Blue Eyes is showing. Bill, growing impatient with keeping silent, verbally explodes in protest after Cornelius suggests doing a probe of Bill's brain to learn more about him. Zira and Cornelius are shocked. While Bill tries to explain who he is and where he came from, one of Urko's gorilla soldiers listens at the door. He q

The Simian Senate is holding a top secret session to debate the rumors of intelligent humans begun after one of Urko's soldiers returns delirious from the Forbidden Zone. He claims to have seen a flying craft fall out of the sky, crash in the dead lagoon and three humans (Bill, Jeff and Judy) emerge and raft to the shores. Gen. Urko demands that all the humans be destroyed, but after hearing all sides, the Lawgiver (Zaius) closes the debate by announcing that the Supreme Council will decide the fate of the humanoids. Later, at a press conference, Zaius and Urko announce their plans to lead an expedition into the Forbidden Zone to verify the soldier's story of a spaceship in the lagoon. Zira and Cornelius decide to warn Bill and Jeff of the expedition. Using a mirror, Cornelius signals the men for a meeting. He explains that if the ship is found, Urko will have all the evidence he needs to begin his annihilation of the humans. The apes believe that Bill and Jeff have infected the humanoids with the ability to think and, as ape law states, they cannot be allowed to gain intelligence. Bill and Jeff decide to beat Urko to the ship, salvage the laser and blow up the spacecraft. Bill asks Nova to lead them to the lagoon. Frightened, she agrees. The next day, Zira and Cornelius watch as the expedition leaves town, worrying for Bill, Jeff, and Nova's safety. As the expedition travels farther into the Forbidden Zone, flames and lightning and other strange images block their way. Urko decides to make camp for the night and proceed in the morning. Suddenly, a flaming skull appears in the sky. The frightened soldiers want to turn back for the City, but Dr. Zaius, skeptical of what they have been seeing, exposes the images as mere illusions. By morning, Bill, Jeff and Nova have reached the lagoon ahead of the army. Luckily, the Venture is still partly above water. They raft to the capsule and Bill swims down to get an oxygen mask out of the ship. The army is advancing rapidly

Bill and Jeff know that the humanoids must be moved to a safer place for protection from Urko and his army. Their one hope is to ask Zira and Cornelius for help in finding a more secure location for themselves and the humans. They secretly hitch a ride into the city on an ape farmer's truck. Meanwhile, Urko reviews his plans for a blistering attack on the humans and orders his aides to search for Blue Eyes. In six days, they will strike. The general hopes to calm Zaius' anger over losing Blue Eyes by capturing all the humans. As night falls, the two men sneak into the city and cross the river in an abandoned boat. A gorilla patrol boat almost spots them, but they are able to reach the shore unseen. While soldiers sweep the area in search of them, the men proceed down a drain pipe into the heart of the city. Barely escaping a giant spider, they emerge from the pipe close to the lab. Inside, Zira is worried that Zaius suspects them of aiding Bill and the humans, but Cornelius argues that Zaius has no proof of their actions. Suddenly, Bill and Jeff come through the window. Bill thanks them for helping him escape earlier and asks Cornelius to help them find a safer place for the humans. Cornelius feels it is disloyal to his country to help, but after Bill points out that humans are no different than any other endangered species, Cornelius suggests a valley which lies to the south of his latest digging site. He has never seen it, but knows of its existence from an old map in the Simian National Library. He promises to make a copy of the map and take them to the general area. Suddenly, a knock is heard on the door. As the men hide, Dr. Zaius comes into the room. He asks Cornelius for a detailed report on Blue Eyes' behavior which may help in locating him and the humans. When Zaius leaves, Cornelius reluctantly agrees to proceed with their plans. The men spend the night in the lab. The next day, the group travels to one of Cornelius' digging sites ninety miles from the

Urko and his army are searching the desert for the entrance to the Underdwellers caverns. Suddenly, Urko spots Bill. He radios Dr. Zaius with the news. Bill plans to decoy the army so that Jeff can slip away. Huge rock pinnacles abruptly jut up from the ground, a hole opens up and a flash of energy shoots out. As the doorway closes, the two men crawl in and ride a conveyor down a dark shaft. Urko feels that the Underdwellers are responsible and proceed to find their caverns. Inside, Bill and Jeff find a giant dish serving as part of an elaborate power system. They know the apes wouldn't have had the technology to build it. They are shocked to find what remains of the New York Public Library among the rubble; this upside-down world is Earth! They pass by Wall Street and Times Square. Zaius tells Zira and Cornelius that Urko has located Blue Eyes. A soldier enters with the news that Blue Eyes has escaped and is suspected to be with the Underdwellers. Zira and Cornelius secretly wonder if they were right in helping Bill escape. Elsewhere, Bill and Jeff enter a huge cavern above a giant power complex operated by hooded and cloaked figures. An alarm rings and the figures begin chanting "Oosa" (USA) over and over. Bill and Jeff discover that the whole complex seems to be wired to a central, throne-like chair. They follow the crowd into another room and spot Judy, also in a hooded robe, standing at the front of the room. Next to her is a tree, a symbol of life on the surface. They call to her, but she only stares into space. Suddenly, a hooded figure shoots a ray out of his eyes and stuns Bill and Jeff. They are awakened in a cell by Krador, who introduces himself as the leader of the Underdwellers, descendants of the humans who sought safely underground during the holocaust long ago. Krador believes that prophecy has foretold of Judy, or USA, helping the Underdwellers return to the surface. Later, Jeff gives Judy a ring which revives her memory. She kills the power on

Bill, Jeff, and Judy are heading for the humanoid settlement across the plain between the mountain ranges when they spot what look like humans far below. Bill calls to them, but Jeff quickly stops him -- the figures are dummy targets. Suddenly, to their amazement, a World War II-era Curtiss P-40 fighter plane appears in the sky. Piloted by a gorilla, the aircraft flies toward the dummies and drops a net on them. Apparently, the Ape army is testing the plane in preparation for war games. Bill concludes that with the plane, there will be no stopping Urko from capturing every human and that they must try to steal it. Later at the ape plane hangar, Urko congratulates Dr. Likis, the ape scientist who restored the flying machine, and wants the aircraft ready for an air demonstration for Dr. Zaius the following day. He then visits Zaius, and demands that Zaius give him complete authority. He backs up his demands with threats of using the plane to secure his power. Zaius, fearing human technology from the past, wants Urko to destroy the plane. Zira and Cornelius receive an invitation at their lab for a demonstration of a new "secret weapon." They see a flash and realize it is Bill signaling them. They all meet in the clearing where Bill tells the apes of Urko's aircraft and their plans to steal it. Cornelius gives them directions to Urko's fortress. Reaching it, the three cause a diversion with some barrels that lets them slip past the guards and find the plane's hangar. They discover that, using the old P-40 fighter as a guide, the apes are building an entire fleet. To make matters worse, humanoids are being herded as target practice in the next day's demonstration. Back at the lab, Cornelius is concerned that Urko, with his hunger for power, might resort to using his air force against apes to gain control of the government. Inside the hangar, Judy thinks that she could fly the P-40 away during the airshow as the plane might be very useful to the humans. The next day al

Bill, Jeff and Judy begin building rafts to help the human tribe reach New Valley on the river and escape Urko's patrols. In Ape City, Dr. Zaius visits Cornelius and Zira in their lab to thank them for stealing Urko's plane. By doing so, he feels that they have saved simian society from Urko's dictatorship. They again assure him that they had nothing to do with the stolen plane, but Zaius insists that their secret is safe with him. He leaves them with the news that Urko has been given permission to attack the human caves to find Blue Eyes. Finally, the rafts are finished and Bill and the others begin the long journey towards New Valley, following the map given to them by Cornelius. The trip takes them through thick jungle growth and swarms of bats. Some of the humans get sick and want to turn back, but Bill decides that they have no choice but to press on. By nightfall, the jungle has given way to a desolate, desert area. Meanwhile, Urko is still enraged over the theft of his plane and orders it found. Since the plane was a military secret, he suspects someone on the inside to be responsible. Urko offers a reward for the thieves' capture and orders the attack on the humans to begin at dawn. Following their map, Bill, Jeff and Judy lead the humans from the rafts across the desert. Despite the terrible heat and wind, they press on. When the army arrives at the river, Urko realizes that the chopped trees mean the humans escaped by raft. Furious that his men are not prepared for water travel, Urko returns to the city for the Council's approval for a water maneuver. The next day, Bill and the others come upon an incredible sight: the wreck of a futuristic United States spaceship! A stranger appears and introduces himself as Ron Brent. He tells them that he has been marooned here since Nova was a little girl. He left Earth on August 6, 2109 from a launch pad in the Mojave Desert. Cape Kennedy had been turned into a museum sixty years before he was born. After crashi

During the night, Ape City is awakened by the sounds of huge, flying objects.

During the night, Ape City is awakened by the sounds of huge flying objects overhead. It is a flying monster, but the apes cannot see it. The Ape Police ready themselves for an attack as Urko arrives. He believes that it is his stolen plane being used in a secret plot to have him overthrown. Zaius later tells the Senate that the flying object has been scared off and that Urko has been given one last chance to find Blue Eyes. In New Valley, Bill and Judy prepare to leave and return with the aircraft. As they watch over their herd of strange animals, the flying monster swoops down and carries one of the calves away, then disappears after entering a cave. Meanwhile, Urko is readying another attack on the humanoids. His aides assure him that the plane is being searched for. During the night, Bill and Judy spot an ape patrol searching for the P-40. The next day, they reach the aircraft exactly where they left it. Judy has trouble starting the engine just as the gorillas approach but is able to lift off at the last minute. Back at the human settlement, the monster has attacked again, causing a stampede. Nova is nearly trampled. The herd is chased into a cave, safe from the monster for the moment. Jeff plans to cut an opening in the hillside so that food can be taken to the herd. Bill and Judy have to risk flying over Ape City in order to conserve fuel. Urko spots the plane and is furious, but Zaius tells Zira and Cornelius that he is glad the aircraft is out of Urko's hands. Bill and Judy reach New Valley just in time to engage the monster in an air battle. After several perilous moments, the P-40 strikes the monster with its landing gear and the beast plummets into the lake below. Bill and Judy land safely, but the monster survived the fall.

Bill, Jeff and Judy begin building rafts to help the human tribe reach New Valley on the river and escape Urko's patrols. In Ape City, Dr. Zaius visits Cornelius and Zira in their lab to thank them for stealing Urko's plane. By doing so, he feels that they have saved simian society from Urko's dictatorship. They again assure him that they had nothing to do with the stolen plane, but Zaius insists that their secret is safe with him. He leaves them with the news that Urko has been given permission to attack the human caves to find Blue Eyes. Finally, the rafts are finished and Bill and the others begin the long journey towards New Valley, following the map given to them by Cornelius. The trip takes them through thick jungle growth and swarms of bats. Some of the humans get sick and want to turn back, but Bill decides that they have no choice but to press on. By nightfall, the jungle has given way to a desolate, desert area. Meanwhile, Urko is still enraged over the theft of his plane and orders it found. Since the plane was a military secret, he suspects someone on the inside to be responsible. Urko offers a reward for the thieves' capture and orders the attack on the humans to begin at dawn. Following their map, Bill, Jeff and Judy lead the humans from the rafts across the desert. Despite the terrible heat and wind, they press on. When the army arrives at the river, Urko realizes that the chopped trees mean the humans escaped by raft. Furious that his men are not prepared for water travel, Urko returns to the city for the Council's approval for a water maneuver. The next day, Bill and the others come upon an incredible sight: the wreck of a futuristic United States spaceship! A stranger appears and introduces himself as Ron Brent. He tells them that he has been marooned here since Nova was a little girl. He left Earth on August 6, 2109 from a launch pad in the Mojave Desert. Cape Kennedy had been turned into a museum sixty years before he was born. After crashi

Reports begin coming in to the police that burglars are striking all over Ape City. Valuable items are being stolen from the Museum, Ape Archives, the Library and from ape homes. A first edition William Apespeare book was taken from Zira and Cornelius' home. Into the night, hooded figures sneak to the cemetery to the Tomb of the Unknown Ape where all the stolen items are hidden. In reality, Urko and his gorillas are disguised as Underdwellers in hopes of framing them and convincing Dr. Zaius to declare war on the below world. Zira and Cornelius travel to New Valley to meet with Jeff, Bill, and Judy. Suddenly, Krador appears and tells them the Underdwellers are innocent of the thefts. He asks them to come to their underground city and bring the laser. Meanwhile, Zaius and the war council hear testimonies of witnesses against the Underdwellers. Unknown to the council, the witnesses are lying as instructed by Urko. Urko assures the council that he can win the war by blowing up the tunnel entrance to the below world. Krador, Bill, and Jeff reach the end of the tunnel underground and Jeff cuts through the wall with the laser. The tunnel connects with the tomb where all the stolen items are hidden. Bill plans to have Cornelius tell Zaius the real truth the next day, but Krador warns that by then Urko will have detonated the tunnel entrance, flooding the world below and causing Ape City to collapse. Krador projects Bill's image into Zira and Cornelius' bedroom where he tells them to take Zaius to the tomb immediately or it will be too late. Krador hypnotizes the guard to awake when Zaius speaks to him and tell the whole truth of Urko's twisted plan. After seeing the stolen goods, Zaius tries to radio Urko to halt the attack, but the general was warned that Zaius knows his plan and he disconnects the radio. Zaius and Cornelius race to the dock to stop Urko personally from sending a barge of explosives into the tunnel entrance. While the Underdwellers hold a final service

Urko has been relieved of his duties for three months because of his recent negligence involving his leadership and the failed attempts at capturing Blue Eyes and the rest of the humans. Col. Rotok will replace him temporarily and Urko insists his men obey Rotok to the letter. In their lab, Zira admits to Cornelius that she actually feels sorry for Urko, but he reminds her what Urko would do to the humans if he returns to power. With Urko out of the picture, they decide to risk a trip to the high mountain apes to retrieve an ancient book proving that man once ruled the planet. Perhaps by showing the senate the evidence, laws will be passed granting man some kind of protection. While they set off to find Jeff and Bill, Urko realizes that another attack on the humans cannot wait an additional three months. By then, their defenses will be even stronger. He convinces Rotok (who remains loyal to Urko) that if he will lead a surprise attack on the still-unprotected west flank of New Valley, they would all be heroes. After Cornelius tells Bill about the book, they decide that the mountain peaks would be too treacherous for the P-40 and to walk would take weeks. Instead, they decide to repair and fly the hot air balloon used to fly to Kigor's mountain once before. Unknown to them, the army is approaching New Valley and a scout patrol is sent ahead to verify the humans' position. Bill and Cornelius decide to make the balloon trip together as a gesture to the High Lama that apes and humans are together in this decision. They are spotted on takeoff by the scouts, whose clumsy driving awakens the monster bird from the lake where it landed following Judy's dog fight with it. The monster attacks the balloon, so Bill steers for the clouds to hide. The scouts report the balloon sighting to Col. Rotok. Everyone wants to delay the attack until the nature of the balloon is known, but Rotok orders the attack to proceed. When Jeff, Judy, and Zira realize that the army is closing in, Jef

During an archaeological dig, Cornelius uncovers an ancient, human book called, "A Day at the Zoo." He explains to Zira that this book would be deadly to the humans if it ever fell into Urko's hands. It might also finally prove their theory that man preceded the ape. Zira places it in the equipment locker just as Urko barges in. Knowing that Cornelius is digging, Urko wants the lab searched for anything that might prove humans are dangerous. But Cornelius refuses to allow a search unless Urko is granted permission from the Supreme Council. Worried, Cornelius considers putting the book back into the ground, but Urko might just dig it up again and it is too valuable to destroy. Suddenly, he notices that the paper he used to wrap up the book at the digging site is actually an old blueprint for a hot-air balloon. Ape-built balloons have always crashed, but Cornelius feels that this design is different and may work. After beginning work on the construction, he is distressed to find that the part of the plan detailing the steering mechanism is missing, probably destroyed by time. They agree that Bill and Jeff may be able to help. When Bill sees the book, he wants to release it to the public so that the truth of the planet will be known, but Cornelius, fearing the public outcry, wants to hide it on the mountain of Ghar. After completing the balloon, Bill and Cornelius cast off. They reach Mt. Ghar, but are forced far off course by a storm. The balloon hits something and crashes. At that moment, gorilla ski-troopers spot the balloon falling out of the sky. While searching for fire wood, Bill and Cornelius come upon a giant ape statue and figure the region must be inhabited. They set out to find help, still watched by the soldiers. The terrible cold is too much for Cornelius and Bill is forced to carry him. They both collapse and are taken to a shelter by apes. When they awake, they are welcomed to the temple of Kigor, god of the mountain apes. Bill asks the High Lama to

Bill and Jeff are discussing the best means of eluding Urko's troops when Judy appears and insists they come to the below world and bring the laser they rescued from the ship. If they delay, Krador and the Underdwellers will perish. The men suspect a trap, but if Judy is in danger, they have to risk the trip. In the below world, Judy and Krador are watching a lava flow on the viewing screen. If it reaches the reactor room, the below world (and perhaps the entire planet) will be destroyed. Meanwhile, Gen. Urko is debating with Zira and Cornelius over how best to use the Senate's money: for defense or scientific research. Dr. Zaius tells Urko that he can have the money if he captures Blue Eyes. Bill and Jeff have decided to hide the laser before journeying to the below world in case they walk into a trap. They are able to enter the underdweller entrance without being spotted by Urko's troops, and meet Judy and Krador, who projects images on the wall of the volcano becoming active again and flooding their caverns with lava. It is getting dangerously close to the reactor room. The laser could cut a new path for the lava to flow away from the below world. Bill and Jeff agree to do the job only if Judy be allowed to leave with them. Krador refuses, believing that she is the fulfillment of prophecy foretelling the Underdweller return to the surface. Finally, he agrees to release Judy if she will return when needed. Meanwhile, gorillas have found the laser and take it to Urko, who deduces that no one --ape, human or Underdweller -- could be responsible for such a weapon except Blue Eyes. Realizing that Bill must be in the area, the army upscales its search. Arriving at the spot where they left the laser, Bill and Jeff see tire tracks and know the apes must have found the laser. Sneaking into the army's camp, the men are able to cause a diversion and reclaim the laser. They proceed to the below world, where they lower themselves into the main cavern and begin blasting throug