 Constanza, princess of Spain, meets Pedro, her promised husband and future king of Portugal. Amidst political intrigue, Pedro falls in love with Inès, Constanza s aid. Inès returns hastily to Spain, repressing her own feelings, but Constanza dies suddenly. Pedro goes against his father s decision to marry a crowned girl, and reunites with his loved one. Three Portuguese nobles, acting in collusion with the king, persecute Inès in a palace, and kill her by the sword. The prince s faction is at the verge of war against their own king, but truce is reached at Oporto. Pedro sulks in agony until his father dies; then, he obtains the extradition of Inès  killers, and exacts terrific vengeance upon them, before crowning Inès as queen, posthumously.