Alcmene, Amphitryon's wife, is High Priestess of the Harvest Festival, a yearly ritual devoted to Hera, which involves the human sacrifice of a male.
The crime is witnessed by a lyre player, Linus, who declares the culprit to be Zeus, due to the lightning symbol on his arm.
The Harpies declare him Son of Zeus, name him "Hercules -- glory to Hera", and order Alcmene to kill him, departing afterward.
One day, Hercules is invited to join his father and King Theseus in a hunt for a wild boar, Ragged-Tusk.
Deianeira confides that the human sacrifices and other barbaric spectacles are not Hera's will, but corruptions brought on by the people in charge of the rituals.
As a reward for saving the town, Hercules is given Megara to marry, but neither she nor their three sons from their earlier encounter love him.
Megara, King Eurystheus (her lover), and Alcmene plot his destruction, for being Son of Zeus and technically, Hera's enemy.
They visit Tiresias, now a prophet, who declares that to atone for his sins, he must perform six labors for King Eurystheus and the now Queen Megara.
He and Linus find them, discovering they are the same Harpies from earlier, and kill them, taking back their heads as proof.
Alone, Hercules finds a seductive, beautiful woman hiding nude in the cave, but she is revealed to be a sphinx turned into human in order to deceive him, and she transforms into her true form to attack him.
They battle, evenly matched, but when Antaeus boasts that his strength comes from the earth itself, Hercules knocks him into a river, rendering him helpless.
Hercules brings him back to Thebes, and suggests locking him in a tower, cutting him off from the earth and keeping him too weak to break free.
For the fourth labor, he must tame the man-eating mares, and give Iole the necklace belonging to their leader.
Jason stabs a mare with his spear; she turns back into a human and cries out in pain as she falls.
The Amazons apologize, saying they had no choice, that it was Hera's bidding, but Hercules picks up the girl who was killed by Jason asking if they really believe that bloodshed and suffering are what the goddess wants.
As Iphicles is stabbed to death as part of the ritual, Megara pulls the distraught Alcmene aside, saying that slow revenge is sweet.
He is shocked and immediately thinks back to the night Deianeira first made love to him, which until now he had thought to be a dream.
For the fifth labor, Hercules must defeat Eurystheus in contest of archery skill, the challenge being to 'bring down' the Ceryneian Hind.
Hercules declares the favor will be the betrothal of Hyllus to Iole, securing a union of the warring families and ending the conflict between them.
Deianeira warns that the Hind is sacred and to spill a drop of its blood is an offense punishable by the gods, but Hercules tells her to trust him.
Hercules deflects the shot by firing an arrow through Eurystheus', and a second through two of the Hinds legs without hitting any of its blood vessels.
In his haste to win the contest, Eurystheus approaches the Hind with intent to kill it, but is stopped by Hercules.
Hercules nevertheless gains the upper hand and nearly drowns his opponent, but Linus finally realizes that he was the one who raped Alcmene, not Zeus.
Tiresias grants that Hercules has completed his last labor and is no longer indebted to Eurystheus, but cautions that the conflict between the two is not resolved.
Hercules comes before Eurystheus, the gathered crowd questioning his victory in the absence of evidence of Cerberus' demise.
Hercules states that he never had any intention of taking the throne, all he wants is for Eurystheus to keep his word and grant the betrothal of Hyllus and Iole.
Immediately after the guard falls dead, Hyllus throws a knife into Eurystheus, fulfilling the prophecy.
Simultaneously, Megara rushes forward to pull Iole from Hyllus, but she is struck in the back with Eurystheus' arrow.
Production on Hercules began on August 23, 2004, with shooting taking place in New Zealand a budget exceeding $20 million.