Burke and Virdon join forces with Leuric, a human attempting to fly by building himself a hang glider.
Burke and Virdon are captured by a bunch of humans determined to hand them over to the Apes.
Thanks to their advanced medical knowledge, Burke and Virdon are able to help a village struck with malaria, but risk discovery.
Aboro, a despot, is making community life a misery; Burke, Virdon, and Galen decide to rob him of his powers.
Burke undergoes a horrific interrogation after being captured whilst Virdon and Galen mount a rescue attempt.
Virdon decides to take part in a dangerous horse race even though he runs the risk of being captured by Urko.
When the guys try to track down the apes who are framing humans for crimes in a small community, Fauna, a blind female ape, falls in love with Burke while believing him to be a chimpanzee.
Galen must use all his charm to try and persuade his ex-girlfriend, a female ape surgeon named Kira, to operate on Virdon using a forbidden human anatomy book, after the astronaut is shot.
An ape who runs a fishing business plans to use Virdon and Burke as slaves after he captures them.
Burke and Virdon are helped by a young woman and a young boy while searching for an underground computer in a ruined city, but their plans go awry when Alan is captured and Urko uses the boy to get information from the astronaut.
Burke and Virdon have to seek the help of a gorilla farmer and his family when Galen falls sick.
In a ruined city, Burke and Urko are trapped underground and must reluctantly work together to escape, while Alan and Galen must deal with Urko's gorilla patrol in the streets above.