Goffredo, the Captain General of the Christian army, is leading his men in attacking Jerusalem. He has also promised the hand of his daughter, Almirena, to the Christian hero, Rinaldo. Argante, the Saracen King of Jerusalem, seeks a truce and works with the sorceress, Arminda, to abduct Almirena. Rinaldo now is resolved to save Almirena but is intercepted by Armida who disguises herself as Alimirena. However, Rinaldo rejects her. Armida's anger is further aroused when Argante, thinking he is addressing Almirena, protests his love for her. Later, with the help of a magic want, Goffredo reaches Armida’s magic mountain. Already, Rinaldo has arrived in Armida’s garden and saved Almirena. With the help of Goffredo and his magic wand, the garden is turned into a desert. Argante and Armida, now reconciled, review their troops and the Christian forces prepare for battle in which they are victorious, thanks to the heroism of Rinaldo. Argante and Armida are taken prisoner. But after they convert to Christianity, they are pardoned.