Orlando, a knight, is torn between glory and love. Zoroastro, a magician, urges him to follow Mars, the god of war, but Orlando decides instead that glory can be gained through the pursuit of love.

Dorinda, a shepherdess, is deep in thought when Orlando rides past with a princess, Isabella, whom he has just rescued. Angelica, the Queen of Cathay, has fallen in love with Medoro, an African prince whose wounds she healed when he was being tended to by Dorinda.

Orlando’s protestations of love to Angelica have fallen on deaf ears.
Medoro declares his love for Angelica. Dorinda loves Medoro. Medoro says Angelica is just a relation. Dorinda doesn’t believe him.

Zoroastro tells Angelica he knows she loves Medoro, and warns her against Orlando’s jealousy. When Orlando arrives, Angelica says he must prove his love for her by renouncing Isabella for ever. He agrees. Now Medoro is jealous. His embrace with Angelica is seen by Dorinda. Angelica buys off Dorinda with a piece of jewellery. Dorinda is inconsolable. She tells Orlando of Angelica’s love for Medoro and shows Orlando the jewel – a jewel Orlando himself had previously given to Angelica –though she says it came from Medoro. When Orlando sees Angelica and Medoro’s names carved in a laurel tree, he threatens to kill Angelica, but Zoroastro intervenes and bears Angelica away in a cloud. Orlando becomes unhinged. Zoroastro takes him away on his chariot. Dorinda, no longer deluded, happily provides shelter for Medoro. Still insane, Orlando arrives, announcing his love for Dorinda. Dorinda tells Angelica of Orlando’s madness, but also says that Orlando has killed Medoro. Angelica is grief-stricken. Zoroastro restores Orlando to sanity. Dorinda tells him he has murdered Medoro.

Distraught, Orlando vows to kill himself. However, Zoroastro has in fact saved Medoro and Orlando is implored by Zoroastro to bless the wedding of Angelica and Medoro. Orlando has gained glory through love.