Act I

Bradamante, disguised as a man, arrives at a party at the island estate of Alcina. She is determined to find and rescue her lover Ruggiero, who has fallen under the enchantress’ spell. Just as she and her former tutor, Melisso, are setting out to explore, they encounter Morgana, Alcina’s sister, who is instantly drawn to the handsome stranger (Bradamante in disguise) and immediately casts aside her lover Oronte.

Alcina arrives in all her glory accompanied by Ruggiero, who is completely under her thrall. They also meet a young boy, Oberto, who is searching for his father. Bradamante and Melisso suspect that, like many of Alcina’s discarded former lovers, his father has been transformed into a wild animal.

Alone at last with Ruggiero, his friends try to reason with him, reminding him of his engagement to Bradamante, but his only thoughts are of Alcina. Oronte, furious at Morgana’s unfaithfulness, challenges Bradamante to a duel. Morgana intervenes, sparing Bradamante but further enraging Oronte, as she is adamant that she no longer wants to stay with him.

An angry Oronte encounters Ruggiero and tells him about the fate of Alcina’s former lovers, and when Ruggiero refuses to believe him, he invents a romance between Alcina and the disguised Bradamante.Morgana arrives and warns Bradamante that Alcina plans to turn him into an animal to prove her devotion to Ruggiero.But Bradamante refuses to flee, telling Mogana that he loves someone on the island and must stay. Morgana leaves ecstatic convinced that she is his beloved.

Disguised as Atlante, Ruggiero’s former tutor, and using a magic ring, Melisso finally shows Ruggiero the truth about Alcina’s island and reminds him of his former life and love. Melissoadvises a horrified Ruggiero to keep his new knowledge a secret, to continue pretending to love Alcina until he can escape under the pretext of going hunting. Bradamante reveals her true identity to Ruggiero who believes that she is just another of Alcina’s enchantments. He is confused, he no longer knows what is real.

Unsure of Ruggiero’s love, Alcina is determined to win it once and for all by transforming Bradamante into an animal, but she is interrupted by an ardent Ruggiero who manages to persuade her against it. Ruggiero asks Alcina permission to go hunting and she grants it. Oronte enters with news of Ruggiero and Bradamante’s plot and Alcina calls upon the gods to witness her distress.

Act II

The besotted Morgana refuses to believe that Bradamante and Ruggiero are in love until she sees them together with her own eyes.

Alcina plots revenge, summoning the spirits to torment her new enemy. But true love has destroyed her powers of illusion and her magic fails. Throughout the mansion, relationships are in crisis.

Morgana pleads for the spurned Oronte’s love once again, while Alcina confronts Ruggiero. But he is adamant in his love for Bradamante, and Alcina’s despair reaches new depths. News that her enchantments and magical forces have been completely defeated by her enemies is another cruel blow, and when Ruggiero and Melisso destroy the magic urn that is the source of all Alcina’s power her defeat is complete. All her spells are broken and across the island all her lovers are once again suddenly human. Alcina, Morgana and Oronteare left alone in the mansion in misery.