Since her son Adelberto is now posing as Ottone, Gismonda poses as Ottone's mother Adelaide in a meeting with Teofane. "Adelaide" haughtily instructs Teofane to give her son her heart as well as her hand (Aria: "Pensa ad amare"), and leaves. Adelberto comes to lead Teofane to their wedding, but his mother reappears with the news that Ottone is invading with an army, thrusts a sword into her son's hand and sends him off to battle. Left alone, Teofane now realises that Adelberto is only pretending to be Ottone, and laments the position in which she finds herself (Aria: "Affanni del pensier").