Gismonda's dream is to see her son Adelberto on the throne of Italy. (Arioso: "Pur chi regni il figlio amato"). When Adelberto comes to her, she informs him of her scheme to bring this to pass. Her deceased husband had ruled Italy illegally as the country was really a possession of the German King Ottone, who is now on the way to reclaim the territory and to marry Teofane, daughter of the Byzantine emperor, who is already in Rome and has been sent a portrait of her bridegroom-to-be, which has caused her to look forward to her marriage with delight. However Ottone has been delayed in his journey to Rome by an attack on his convoy of ships by pirates, necessitating a battle at sea. Gismonda instructs her son to present himself to Teofane as her bridegroom, and then marry her, pretending to be Ottone. Adelberto thinks this is a very clever plan and Gismonda joyfully anticipates her son's success. (Aria: "Giunt'in porto").