Act I

Ercole (Hercules) has defeated the Kingdom of Oechalia and killed its ruler, Eutyro. Ercole loves Eutyro's daughter Iole, but she is betrothed to Ercole's son Hyllo. Venere (Venus), goddess of love, arrives with the Graces and decides to help Ercole win Iole by casting a spell on her. Hearing of Venere's work, the goddess Giunone (Juno) decides to thwart Venere and Ercole.

Act II

The lovers Hyllo and Iole learn of Ercole's interest in her. Giunone sings that she will stop Venere. Pasithea, one of the Graces, goes to the cave of Sleep to seek his help in Venere's plans.

Act III

Ercole is in a deep slumber. Iole moves to kill Ercole, seeking to avenge her father. Ercole is awakened by the god Mercurio (Mercury). Ercole believes Hyllo was trying to kill him and wants his son dead. Dejanira, Ercole's wife, pleads for their son. Iole promises she will accept Ercole if he will spare Hyllo. Ercole exiles his wife and orders Hyllo confined to a tower overlooking the ocean.

Act IV

Hyllo jumps from his tower into the sea intending suicide. But Giunone calls upon Nettuno (Neptune), god of the sea, to save Hyllo. Iole and Dejanira do not know of the gods' intervention and believe Hyllo dead. They go to the grave of Iole's father. Eutyro's ghost appears, warning Iole she should not marry Ercole. Venere continues her schemes by creating an enchanted chair. When Iole sits in it, she feels affection for Ercole.

Act V

In Hades, Eutyro and the other victims of Ercole sing. Licco, a servant of Dejanira, plots to disrupt the wedding. At Licco's behest, Iole offers Ercole a shirt soaked in the blood of the centaur Nessus, who Ercole had killed. Ercole is poisoned by the shirt and dies. Giunone appears, triumphant, with Hyllo. He reunites with Iole. Ercole ascends to Heaven and marries Beauty.