Following the first mission’s space-time trajectory, astronaut James Franciscus arrives to investigate what became of the original crew. Trekking into the Forbidden Zone in search of Charlton Heston, and guided by Heston’s mute female mate Linda Harrison, he discovers a race of telepathic human mutants that worships a doomsday nuclear weapon. Meanwhile the ape army of militaristic General Ursus (James Gregory) is on the warpath. The only original Apes movie without Roddy McDowall but with Planet vets Kim Hunter and Maurice Evans as well as Victor Buono and Gregory Sierra.