in the roman forum, the emperor valentiniano (valentinian iii) and the people welcome ezio, who is returning in triumph, having defeated attila and saved the empire. ezio greets his sweetheart fulvia, daughter of massimo, who although close to the emperor has never forgiven him for trying to seduce his wife and thirsts for vengeance. massimo tells ezio that in the latter's absence the emperor has fallen in love with fulvia and now insists on marrying her himself. the only way to prevent this, according to massimo, is to assassinate the emperor, but ezio refuses to have anything to do with such a plot. alone with his daughter, massimo tells her that if ezio will not kill the emperor, she must first marry and then kill him. fulvia rejects this idea with horror. massimo decides that since neither ezio nor fulvia will kill valentiniano, he will send one of his henchmen to do it.