The action takes place partly in the fortress of Canosso near the lake di Garda in Lombardy, Italy, and partly in the camp of Ottone, in the year 947. The story is based on historical facts. Berengario and Adelberto were tyrannical traitors, Adelaide generous and sensible: Ottone magnanimous but not enough cautious.

Synopsis

Berengario has poisoned Lotario, first King of Italy and usurped the throne. Adelaide of Burgundy, the widow of Lotario, confines herself in Pavia to avoid the persecution of Berengario, who wants to constrain her to marry his son, Adelberto, in order to assure his authority. There, henchmen of Adelberto sieged her, but she was rescued and taken to the fortress of Canosso. Berengario sieged her once again and rather than succumb to him, Adelaide sought the help of Ottone the Great, Emperor of Germany. Ottone, defeats Bergenario and marries Adelaide himself.