Hercules, at Olympus, berates his father Zeus for not allowing him to leave the gods' abode to adventure on earth. Eventually Zeus sends Hercules, on a beam, to the land of men.
After some strange encounters in the air and at sea, Hercules arrives in New York City, where hilarity ensues in the form of interactions with various New Yorkers, who regard him as physically superior but socially awkward. He meets a skinny little guy called Pretzie (Arnold Stang). Hercules becomes a successful professional wrestler.
Zeus, watching Hercules from the heights, becomes irritated with Hercules' antics, which he feels are making a mockery of the gods, and calls on Mercury to stop Hercules. After Mercury makes an unsuccessful attempt to bring Hercules home, Zeus orders Nemesis to see to it that Hercules is consigned to the infernal regions ruled over by Pluto.
However, Juno instead convinces Nemesis to poison Hercules with a poison that would strip him of his divinity and then talk to Pluto. Nemesis informs Pluto of what is happening and he bets a large sum of money against Hercules in an upcoming strongman competition with Hercules' gangster manager.
When Hercules loses the strongman competition his friends try to lead off Hercules' angry manager's henchmen, but Hercules follows them to save them.
Meanwhile, Zeus uncovers the truth from Nemesis as to what is happening but only intervenes at the last minute to restore Hercules' divinity, not wanting any son of his to die at the hands of a mortal.
Hercules defeats the gangsters and realizes that he has been disobedient and returns to the heavens shortly after, only saying good-bye to Pretzie over a radio after he leaves.
In the heavens, Zeus tells Juno and Hercules that he is not going to punish Hercules for his behavior as they ask him about it and then asks to be left alone. They leave him alone, and upon their departure, Zeus sneaks out of the heavens and descends to earth, scaring a passenger jet on his way down.Arnold Stang - Pretzie
Arnold Schwarzenegger - Hercules (credited as Arnold Strong "Mr. Universe")
Deborah Loomis - Helen Camden
James Karen - Professor Camden
Ernest Graves - Zeus
Tanny McDonald - Juno
Taina Elg - Nemesis
Michael Lipton - Pluto
Playing the film's title character, Schwarzenegger, because of his long last name and to play off the name of fellow cast member comedian Arnold Stang, is credited as "Arnold Strong 'Mr. Universe'".
According to Schwarzenegger's autobiography, he had all his lines dubbed due to his thick Austrian accent , although the Trimark DVD has an "Original English Dialogue" audio track with Arnold's voice. However, in the film's final scene, Hercules speaks to over a small transistor radio in a voice that is not Schwarzenegger's. This inadvertently makes Pretzie look crazy or senile.
On October 19, 2006, the San Francisco Chronicle reported that Premiere Pictures was auctioning off the rights to the film on eBay for a minimum bid of $550,000.