A secret agent works with a scientist to recover documents outlining a new formula to make fuel.

A helicopter crashes in the desert, and the crew winds up in the underground city of Atlantis and get mixed up in a slave revolt.

Muscleman fights sea monsters and Amazon warriors, then returns home to find a race of giants living in a valley, into which fellow countrymen are being thrown as punishment for opposing a usurper king and his consort.

Maciste travels to Egypt, where he leads a revolt against an evil queen. In Son of Samson, Maciste (Mark Forrest) -- scion of the famed muscleman -- travels to the Egyptian city of Tanis to checkmate villainous Queen Smedes (Chelo Alonso), who's persecuting the citizenry.