Shepherds and nymphs rejoice at the wedding of Orfeo and Euridice. The bridal couple proclaim their perfect happiness and make their way to the temple to offer tribute.

Orfeo, happy to be in his home country of Thrace, comes to make merry with the shepherds, turning the very air to gold with his song. Silvia, the Messenger, bursts in with the news that Eurydice has been bitten by a serpent and is already dead. Orfeo is stunned. He refuses to believe they can ever be parted and vows to find her in the underworld, either to bring her back to the light of the day or to remain in Hades with her forever. Grief-stricken Silvia retires to mourn alone. The shepherds lament.

At the gates of hell, Orfeo is visited by the goddess Speranza (Hope), who encourages him to seek Euridice in the underworld. She regretfully must leave him there, for the sign reads, “Abandon all hope, ye who enter.” Refused passage across the Styx by Caronte the boatman, Orfeo nevertheless sings his way into Hades, singing Caronte into a deep sleep. The Spirits champion the enterprising and undaunted human spirit.

Proserpina begs her husband Plutone, in the name of their love, to release Euridice. The Spirits second her plea. Plutone relents and allows Orfeo to reclaim her on the condition that he not look back at her while he is leading her home. Fearing deceit, he looks back. All is lost. She is forced to remain, and he is forced back to the land of the living. The Spirits remark that a man may conquer hell, but if he conquer not himself, he has not won the victory.

Orfeo wanders the Thracian fields alone with his redoubled grief. His father Apollo, god of music, appears and invites him to join the gods, where he will be able to see Eurydice from the stars. They ascend to Heaven together.