Gustavo (King of the Cimbrians) solemnly swears vengeance upon Faramondo (King of the Franks), by whose hands Gustavo's son Sveno was slain. The man who brings King Gustavo Faramondo's head will be rewarded with Gustavo's daughter Rosimonda's hand in marriage and his throne. Into this tense situation comes the captured Princess Clotilde (sister to Faramondo), whom Prince Adolfo, Gustavo's surviving son, loves – and it is only by his pleading for her that Clotilde is not slain. Once the two young lovers are left alone, Clotilde extracts a promise from Adolfo to change his allegiance to her brother Faramondo, for love of her.