Set in Seville, the play concerns a feud between the houses of two Spanish aristocrats, Don Pedro de Vitelli and Don Ferdinando de Alvarez. Twenty years earlier, Alvarez had killed Vitelli's uncle in a duel, and had fled Spain with his small son Lucio, leaving behind his wife Eugenia and daughter "Posthumia." In the play's opening scene, Vitelli reveals that Alvarez has been pardoned by King Philip and is returning to the city. Serving during the Siege of Ostend, Alvarez's son Lucio distinguished himself for bravery, and as his reward begged his father's pardon. Vitelli, however, is determined to fulfill the demands of his code of honour and obtain revenge for his uncle's death.