Johnny Barrett, an ambitious journalist, is determined to win a Pulitzer Prize by solving a murder committed in a lunatic asylum and witnessed only by three inmates, from whom the police have been unable to extract the information. With the connivance of a psychiatrist, and the reluctant help of his girlfriend, he succeeds in having himself declared insane and sent to the asylum. There he slowly tracks down and interviews the witnesses - but things are stranger than they seem ...

Cornelius and Zira's son Caesar leads apes to revolution in this installment of the apes saga. Dogs and cats have been wiped out by a plague and now apes are household pets that are treated like slaves. Caesar has the intelligence to fight this oppression.