In 454 A.D. barbarians led by the Vandal king, Genseri, besiege Rome which is ruled by the ineffectual Valentinian III and his wife, Calpurnia. The Roman general Ezio manages to temporarily halt the Vandals' advance. Now arriving on the scene is Ezio's son, Fabius, who had been reported as killed in battle. Fabius falls in love with Valentinian's daughter, Priscilla, while coming to the realization that Rome is weak and corrupt. Genseri now hatches a plan to take over Rome by marrying his son to Priscilla, To prevent this, Fabius hides Priscilla but is then captured and tortured by Genseri who wants to know the young woman's whereabouts. Priscilla comes forward and agrees to marry Genseri's son if Genseri will free Fabius. Genseri agrees but, at the wedding, he breaks his word and shows Priscilla a cross where Fabius has been crucified with ropes. Priscilla is outraged but then relieved when Fabius' friends arrive to save Fabius and to defeat the Vandals in battle.