The plot is based on an episode in Matteo Boiardo's unfinished epic poem Orlando Innamorato ([orˈlando innamoˈraːto]).

Orlando defeats but spares Argillano, leaving the magic sword on the ground as he severs the golden branch, thus opening the way for everyone into Ersilla's garden.

Spurned by Ersilla, Argillano vows to betray her, and to gain an accomplice, falsely pledges his love to Tigrinda.

Under cover of “madness,” Orlando tells the bizarre story of how Origille betrayed him last time they met.

Grifone's pledges of love are rejected by Tigrinda, who then plots with a reluctant Argillano to poison Ersilla with a magic potion.

Ersilla's darkest ceremony fails to reveal Orlando's true identity, so she conjures up a counterfeit Angelica to provoke him.

Orlando smashes his fetters, releases Brandimarte, and by destroying Ersilla's castle, breaks all her spells.