After a young man is killed in an unexplored subterranean cavern and his girlfriend driven mad by something she saw there, a track found at the scene cannot be identified with any known animal and thus a scientific expedition is launched to find out just what it is that is living there.

A Nazi scientist using the lost city of Atlantis as his home base threatens to destroy civilization with a nuclear bomb. The Nazi scientist wants the third Reich to rule again and if his demands are not meet he will follow through on his threat of nuclear annihilation. With very little time to spare Santo is enlisted to find the nuclear bomb, disarm it and end the Nazi scientist’s diabolical plan

Bruno Halder a sinister scientist seeking revenge against his brother and niece is resurrected by Waldo his faithful sidekick. Besides his minions of zombies Halder enlists the help of Wolfman, Franquestain, a Vampire, a Mummy and a Cyclops. Once again the survival of mankind is put in the hands of Santo