Planet of the Apes#3(1974)

Alexander and Jason continue their flight through the subterranean mutant caverns in search of the missing Lawgiver – the only ape that can clear Jason’s name. A squad of Brutus' renegade gorilla soldiers closes in on them, but they manage to divert their course into the path of a gang of angry mutant drones. While ape battles mutant, the two refugees sneak off further into the tunnels. Another throng of mutants manages to corner them, but Jason succeeds in grabbing one of their scorch weapons. They blast their way past several mutant guards until they find an abandoned railcar. An elite unit of mutants known as the Inheritors stops the car and capture Jason and Alexander. They bring them to the Gestalt Chamber where they encounter the Inheritor leader – a collective consciousness constructed of three disembodied brains. The Inheritor tri-brain sentences them for execution in a battle arena. In the pit arena, Jason and Alexander find another prisoner – one of Brutus' renegade gorilla soldiers. All three are forced to team-up in order to fight up against several horrific monsters. Escaping from the pit, the three fight through several more drones until they come to the prison cell of the Lawgiver. Jason frees the Lawgiver who tells them of a tunnel that will lead them to a sky-ship. They find a futuristic hover-ship and miraculously discover how to operate it. As more mutant drones converge on their position, Jason, Alexander, and the Lawgiver rocket their way to freedom.