Tragedy about Don Alvaro, who loves Leonor, daughter of the Marquis of Calatrava, but whose suit the marquis rejects because Don Alvaro's mother was not of noble birth. As the couple prepare to elope, the marquis apprehends them, but he is mortally wounded when Don Alvaro's pistol accidentally discharges. Dying, the marquis curses Leonor. Years pass, and now Leonor is a hermit living in a cave in the vicinity of a Franciscan monastery, while Don Alvaro and Don Carlos, Leonor's brother, who has sworn vengeance on the lovers, are soldiers in Italy. Neither man knows the true name of the other, and, each having saved the other's life, they become fast friends until their identities are revealed. Now the two are forced to duel, and Don Alvaro kills Don Carlos.
Years later, Don Alvaro withdraws to the same monastery, where he becomes a paragon of humility. Don Alfonso, Leonor's remaining brother, seeks him out and compels him to duel. Alfonso, fatally wounded, begs Alvaro to fetch him a priest. Alvaro goes to the hermit's cave and, mistaking Leonor for a monk, forces her to follow him. Alfonso recognises her immediately, and as she stoops over him, he stabs her in revenge. When he realises the tragedy, Don Alvaro hurls himself over a precipice.