Like Hercules before it, This film's story mixes together various elements of different myths and ancient Greek plays. Purists will not enjoy this but fans of these films have to acknowledge that it is this kind of treatment which has allowed the Greek myths to survive and remain popular. Films like this one paved the way for future films and television shows like Hercules: The Legendary Journeys which frequently mixes and matches myths to serve its stories.
The film follows from its predecessor. After travelling about by sea for sometime, Hercules and his wife, Iole (Sylvia Koscina), land near Thebes. Hercules visits his friend Oedipus who has left his throne to his two sons, Eteocles and Polynices, who are to rule together, switching each year. This year, Eteocles declines to yield the throne to his brother and Oedipus asks Hercules to help sort the situation out.
Hercules leaves Iole in the care of the high priest Creon (Carlo D'Angelo) and sets off with his young friend Ulysses (Gabriel Antonini). Their journey is fraught with difficulty. Hercules must battle the giant, Antaeus (Primo Carnera). Hercules defeats him, of course.
Before reaching his destination, Hercules drinks from a fountain of forgetfulness. He loses his memory of who he is and of everything he knew. With Hercules incapacitated, Queen Omphale's men arrive to take the hero to their queen who has an appetite for beautiful men. Ulysses pretends to be a deaf and mute slave so he will be unharmed and taken along to Lydia with Hercules.
Hercules is taken to Queen Omphale (Sylvia Lopez) and she has him perform various labours for her (not the least of which is sexual). We are made to believe that Omphale usually uses and disposes of men quite quickly but that she has actually fallen in love with the amnesiac Hercules. Omphale continues to have Hercules drink the waters of forgetfulness so he will not leave her and Ulysses tries desperately to make Hercules regain his memories.
Finally, Ulysses is able to get fresh water to Hercules and he begins to remember who he is. He eventually confronts Omphale who agrees to release him rather than killing her great love. It's just in time because back in Thebes, Iole has fallen under the horrible care of the tyrant Eteocles. He plans to use her as a hostage to stop Hercules from assisting his brother.
Hercules cleverly proposes that the brothers fight each other in single combat rather than have their armies slaughter each other. Eteocles agrees. He defeats Polynices but not without receiving a killing blow himself.
The people elect the good priest Cleon as their new ruler and Iole is saved. However, it is strongly implied that she has suffered rape at the hands of Eteocles. The ending is far from happy as Hercules tenderly approaches her, hoping they may someday be happy again.
This film is not nearly as entertaining as its predecessor. It's boring and Hercules actually has very little screen time. Far more of the film is spent on the boring subplot of the maniacal Eteocles as he abuses his people and everyone around him. When Hercules is on the screen, he is mostly amnesiac and not especially interesting to watch. There are no epic battles, no monsters and Hercules and Omphale's "love affair" lacks any kind of depth or romance.
This would be the last outing for Steve Reeves as Hercules, though he would go on to play other heroic characters in several more sword and sandal films. Sylvia Lopez was a French model turned actress. While filming Hercules Unchained, Lopez had leukemia. She was only able to complete one film after this one. The cinematographer on this film was Mario Bava who went on to become a prolific director and cinematographer of gory Italian horror films well into the 1970s.
This film is in the public domain so it has been released in various editions on DVD. It can also be viewed online at the Internet Archive.