The film opens at Gene Sys (pronounced “Genesis”), a genetic therapy pharmaceutical company. (Plot sidenote: Genetic therapy is real science. A virus is used to deliver new genetic material to a living organism, thus changing its DNA. This works on children and adults, whereas most genetic manipulation would take place before or at fertilization.)
Female ape (name? a key character) is woking the tower puzzle. She solves the puzzle in 20 moves; 15 is a perfect score. She is more sociable, calm, than normal apes. Will Rodman (Franco) talks to his boss, Steve Jacobs (Oyelowo), and convinces Jacobs that he has data to proceed with human trials. Female Ape is proof that ALZ 112 works. They must present to the board and get approval.
Cut to Rodman and Franklin in conference room presenting to the board the next day. The new drug causes neurogenesis, which allows the brain to grow new brain cells (something that doesn’t happen after birth) and heal any number of degenerative brain disorders, such as Parkinson’s or Alzheimer’s. The only side effect is turning the eyes green.
Meanwhile in the lab, Robert Franklin (Labine) is the senior ape caretaker. He cannot coax female ape out of cage. She is late for her appearance before the board. They finally get her out of bed with orange soda and try to wrangle her. She goes “ape.” With newfound intelligence, she can now use the lasso pole against the lab techs. A chase ensues, which ends in the lobby, and female ape crashes through the glass into the conference room. Security guards fire about 6-10 rounds into female ape and take her down.
Jacobs pronounces the drug project dead. The risk of violent side effects is too high. Rodman appeals, but Jacobs heads straight to the lab and tells Franklin to dispose of the apes. He appeals to his humanity, but Jacobs is insistent in the the danger.
Later in the day, Rodman meets Franklin in the lab. Female Ape, as it turns out, was not violent due to the drug, but had just given birth and was protecting her child. Franklin did not have the heart to give the baby the lethal injection. He tells Lando to take the baby home or to kill it. Lando reluctantly agrees.
At home, we find out Lando’s secret motivation. The nurse is leaving, commenting, “He has had a bad day.” Someone is playing the piano in the next room.. badly. I IS Charles Rodman (Lithgow), Rodman’s father and Alzheimer victim. The baby ape turns out to be therapy (both social and activity) for father. Father names him Caesar, after Julius Caesar (implied, after his favorite Shakespeare play.)
Cut to three years later. Caesar walks out of the bathroom as we hear the toilet flush. We get to follow Caeser through the house. He swings from chandeliers, moving naturally as ape through the house, all the way up to the attic, which is his room. He likes to watch the neighborhood out the window. Caesar is adept at sign language, and communicates complex ideas and statements.
Father is in altercation with nurse. Rodman steps in, and nurse states he needs to go into a home for his own safety. He has a gash in his hand. Rodman decides to steal ALZ 112 and treat his father, who is reborn overnight.
Caesar feel the call of the wild and decides to sneak outdoors, then into neighbor’s house, scaring Alice Hunsiker half to death. Mr. Hunsiker (Hewlett) is chasing Casear through his house with a bat. Father hears the commotion and rescues Caesar from a good beating. Caesar has a deep gash in his right leg.
Rodman takes Caesar to the zoo, sneaking him in a baby carriage. He takes him to the vetenarian, Caroline Aranha (Pinto). She stitches him up. Caesar insists she come over for dinner. Rodman and Aranha develop a romance. She marvels at how smart Caesar is.
To counter Caesar;s wanderlust, they take him across the golden gate bridge to the Red Oak forest, for play time. Caesar will not leave Rodman, but makes supplication gesture of extending out arm, palm up. (He asks for permission to play.) Aranha explains this to audience & Rodman. Rodman lets him.
Five years later. Aranha has married Rodman (confirm?), and is now living as part of family.
ALZ 112 is no longer working for Father. Rodman reasons his immune system has developed antibodies and a more aggressive virus is needed. Rodman goes to Jacobs, confesses his secret experiment with his father, explains the drug not only repairs, but makes people smarter. He says he has reworked the virus and needs Jacobs to approve new animal testing.
Meanwhile, Father is at home. He gets confused and goes out to the street and gets in neighbor Hensiker’s car, which has keys in it. Father tries to drive, but only hits car in front and behind multiple times. Hensiker is furious, and pulls Father out of the car, yelling, shouting, pointing finger. Father is confused, and is now getting upset.
Caesar’s instinct kicks in and he responds to threat to his family. He throws Hensiker to the ground, climbs trees, jumps down again on top of him. He bites a finger off. “Casear, no!” yells Father; he is no longer foggy. Caesar stops. Caesar is sent to “jail” – a primate sanctuary. Rodman and Arahna walk him in and say good bye.
First day in the preserve is tough. Lucky (the alpha male ape) tears off Caesar’s shirt and beats him up. Later, mean caretaker Dodge Landon (Felton) responds violently to Caesar’s challenge to his authority by turning the firehose on him. Caesar discovers an orangutan across the aisle from him speaks sign language.
12 Apes are shipped to Gene Sys from the primate preserve, but lucky is not one of them. The first ape exposed to ALZ 113 (the new, more aggressive virsu) is one of Caesar’s friends. He struggles slightly when exposed to the new drug, accidentally exposing Franklin to the ALZ 113.
That night, Rodman takes ALZ 113 to treat his father. Father refuses treatment, and dies that night in his sleep. Rodman takes 2 days off work for the funeral.
Meanwhile, Dodge brings his friends to the preserve and Caesar manages to steal a pocket knife from one of the boys. Caesar can now use the pocket knife to unlock his cage and run errands at night. He befriends the large Gorilla in the yard, who is never let out of his cage, by letting him loose. He then releases Lucky, who ventures into the yard. Caesar hits him with a steel gas can. Lucky realizes that the Gorilla is loyal to Caesar, and submits. Caesar is now the alpha male. Caesar lets Lucky out of the cage and allows him to give stolen cookies (from Dodge) — one to each ape, solidifying the solidarity of the group. Caesar finds a way out through the roof.
Rodman returns to work, where Jacobs has greedily pushed the research schedule ahead wrecklessly. Rodman and Jacobs argue. Rodman states, “We don’t know how this will affect humans yet.” Franklin, nearby, sneezes blood, as he has been infected by RLZ 113. Rodman quits and decides to break Caesar out of the preserve. He bribes John Landon (Cox and father of Dodge) to let Caesar go. Caesar refuses to go with him.
That evening, Caesar busts out, through the window he found, and goes back home. He steals ALZ 113 from Rodman’s refridgerator, and gives it to the apes at the preserve. The next day, John Landon observes the apes having something like a conference. The apes scatter, playing it off. Landon dismisses it as just something weird.
That night, the apes bust out of the preserve. Caesar does not return to his cage, confronting and defeating Dodge in the yard. He speaks for the first time, shouting “No!” The other caretaker witnesses this and runs into the cage area, trying to rescue the now unconscious Dodge.
The apes attack him, but Caesar calls them off and gives him mercy, putting him in his cage. Dodge tries to escape and gets killed. (He is holding a tazer and Caesar hits him with fire hose.)
At Dawn, Lando tries to call to check on Caesar. No one answers at the preserve. He drives out to the preserve to investigate. He finds it wrecked. He finds the ALZ 113 canisters. He decides to raise the alarm.
Meanwhile, the apes are now crossing town, heading separately to the zoo as a liberation force and to Gene Sys.
Meanwhile, because he is sick, Franklin goes to Rodman’s home, seeking help. Hunsiker confronts Franlin, who is snooping around his neighborhood. Franklin accidentally sneezes on him when he is startled.
Jacobs gets a phone call from lab assistant. Franklin was found dead in his apartment. ALZ 113 is lethal to humans. Their conversation is cut short when the apes attack Gene Sys, liberating the 12 fellow test subjects.
At the zoo, the big Gorilla smashes the ape cage and the apes are loose. The apes take pieces of the cage, shaped like spears.
Begin climactic action sequence.
Now some 50-60 apes, chimps, and gorillas strong, the group heads through town to the Golden gate bridge. They are headed to the Red oak forest. Animal control catches an ape, who is liberated by his fellow apes throwing spears at the truck. The apes seem to be intentionally preventing human deaths.
Fog has rolled into the bay, and visibility ont he bridge is about 40 feet. The apes stop traffic and cause mayhem. The police barricade the other end of the bridge. Caesar sees the ambush, and so sends the apes to climb the cables of the bridge and the structure underneath to ambush the ambush. The apes overwhelm the police force and send them running, with minimal casualties. Jacobs arrives in his helicopter and begins to use automatic weapon fire to lay waste to the apes. The big gorilla heroically jumps off the bridge onto the helicopter and brings it down, but suffers mortal wounds.
The apes proceed unabated to the forest.
Rodman is giving chase, and gets through the baricade in a stolen police car to catch up with Caesar. He finds Caesar and urges him to come home. Caesar speaks “I am home.”
Hunsiker comes out of his house in a pilot’s uniform. He drives to work. In front of the flight board, he has a nose bleed. The camera pans up to the flight board, suggesting all these places will soon be infected wih RLZ 113, sealing mankind’s fate