En route to Thebes for an important diplomatic mission, Hercules drinks from a magic spring and loses his memory. He spends most of the movie in the pleasure gardens of Queen Omphale of Lydia. While young Ulysses tries to help him regain his memory, political tensions escalate in Thebes, and Hercules' new wife Iole finds herself in mortal danger.

Hercules is summoned to oppose the evil Queen Samara, who has allied herself with aliens and is sacrificing her own people in a bid to awaken a moon goddess.

Four muscular heroes fight the evil ruler of an oppressed people.