An evil alien brain, bent on world domination, takes over the body of an atomic scientist, while a “good” alien brain inhabits the body of the scientist’s dog and waits…

To keep peace, an Army captain (Willard Parker) hunts for an outlaw-gang leader (Kent Taylor) who is raiding Indians.

A young boy lets the animals out of their cages at the Zoo, to set them free, but the animals start taking over the town.