In a prologue the Music introduces us into the story, a demonstration of the power of music.
In the first act Orfeo and Euridice are at last to marry, an event celebrated in dance and song by a company of shepherds. Orfeo and Euridice sing of their love for each other.
The second act continues the celebration, but this is interrupted by the appearance of the Messenger. She breaks the news of the death of Euridice - she was bitten by a snake while gathering flowers. The Messenger leaves and declares she will shun human company from now on, living lonely in a cavern to reflect her sorrow.
In the third act, Orfeo accompanied by Speranza (Hope), sets out for the Underworld. She leaves him as he approaches the Styx, eventually overpowering the boatman of the dead, Caronte, with his music, and crossing the river.
In the fourth act, in the kingdom of Pluto, Proserpina has been deeply affected by the music that Orfeo brought. She pleads with her husband for the release of Euridice. Orfeo’s young bride is released, on one condition: as she follows Orfeo, he must absolutely not turn to look at her. As he walks away, doubts assail him and he looks round, only to lose Euridice, who must now remain in the Underworld.
The fifth act finds Orpheus alone in the fields of Thrace, comforted by Echo. Apollo appears as a deus ex machina, descending in a cloud to raise Orpheus to the sky, where he can spend eternity gazing on Euridice’s likeness in the stars.