Teofane walks dejectedly in the garden, feeling utterly alone (Aria: "S’io dir potessi"). Emireno and Adelberto emerge from the tunnel, pushing the stone aside. They have escaped from prison with the help of a map sent to them by Matilda. Emireno looks forward to freedom and to vanquishing the enemies who have wronged him (Aria: "Le profonde vie dell’onde"). Emireno goes to find the boat Matilda has told him will be waiting, and Matilda herself, then Ottone arrive, Matilda looking for the tunnel and Ottone in search of Teofane. Adelberto and Teofane conceal themselves as Matilda guides Ottone away, telling him it is not safe for him to wander around at night alone. Ottone is more concerned about Teofane than himself (Aria: "Deh! Non dir"). Emireno has found the boat and returns, and Adelberto seizes Teofane, who swoons as he carries her into the boat and rows her away, together with Emireno and some of their men. Gismonda joins Matilda in the garden; they celebrate the night that saw the success of their plan to free Adelberto (Duet: "Notte cara").