Ten years after the global pandemic of a deadly Simian Flu, the worldwide human population has been drastically reduced, with only about one in 1000 genetically immune. Civilization is destroyed from the result of societal collapse. The apes, under the chimpanzee Caesar, all bestowed with genetically enhanced intelligence by the virus, have long-established a colony in the Muir Woods near San Francisco.
A group of humans, led by a man named Malcolm, trespass the apes’ territory from San Francisco in search of a hydroelectric dam that would restore power to the city. An encounter by Caesar’s son Blue Eyes and his friend Ash leads to the latter’s injury by a man named Carver. Malcolm manages to prevent further escalation, and Caesar orders the humans to leave. Prompted by Koba, a scarred bonobo who holds a personal grudge against humans for his mistreatment as a laboratory test subject, Caesar brings his army to the humans’ community as a display of strength. Caesar announces to the community that while the apes do not want war, he intends to fight the humans if he is forced to, while demanding the humans stay in their territory. Malcolm convinces his fellow leader Dreyfus to give him time to take a small team to the forest and reconcile with the apes so they can access the dam. He meets with Caesar, who allows them to work on the generator on the condition that they surrender their guns. As Malcolm, his wife Ellie, and his son Alexander work, they bond with the apes. The fragile bonding is greatly helped when Ellie, a nurse, effectively treats Caesar’s wife Cornelia’s illness.