A rescue team from earth lands their flying saucer-like spacecraft on an alien world, to discover they are not only not welcomed by the lone survivor of a missing scientific expedition sent there two decades earlier, but, once they have determined to investigate the deaths of his colleagues and bring him back home by force, along with his planet-born daughter, find themselves subjected to assault by something invisible which seems intent on preventing them from leaving the planet, ever.

Astronaut Brent is sent to rescue Taylor but crash lands on the Planet of the Apes, just like Taylor did in the original film. Taylor has disappeared into the Forbidden Zone so Brent and Nova try to follow and find him. He discovers a cult of humans that fear the Apes’ latest military movements and finds himself in the middle. Tension mounts to a climactic battle between ape and man deep in the bowels of the planet.

Three women makes an emergency landing on a planet plagued with a fatal disease, but are captured by dictator Overdog. Adventurer Wolff goes there to rescue them and meets Niki, the only Earthling left from a medical expedition. Combining their talents, they try to rescue the women.

In the distant future, a federation marshal arrives at a research lab on a remote planet where a genetic experiment has gotten loose and begins feeding on the dwindling scientific group.

The ultimate showdown on a forbidden planet.