Characters
| Count Walter | Bass |
| Rodolfo, his son | Tenor |
| Miller, an old soldier | Bass |
| Luisa, his daughter | Soprano |
| Frederica, Duchess of Ostheim, Walter's niece | Contralto |
| Laura, a peasant girl | Contralto |
Ladies attending the Duchess, pages, servants, archers, and villagers.
Luisa is the daughter of Miller, an old soldier. There is ardent love between her and Rodolfo, the son of Count Walter, who has concealed his real name and rank from her and her father and is known to them as a peasant named Carlo. Old Miller, however, has a presentiment that evil will result from their attachment. This is confirmed on his being informed by Wurm that Carlo is Rodolfo, his master's son. Wurm is himself in love with Luisa.
The Duchess Frederica, Count Walter's niece, arrives at the castle. She had been brought up there with Rodolfo, and has from childhood cherished a deep affection for him; but, compelled by her father to marry the Duke d'Ostheim, has not seen Rodolfo for some years. The Duke, however, having died, she is now a widow, and, on the invitation of Count Walter, who has, unknown to Rodolfo, made proposals of marriage to her on his son's behalf, she arrives at the castle, expecting to marry at once the love of her childhood. The Count having been informed by Wurm of his son's love for Luisa, resolves to break off their intimacy. Rodolfo reveals to the Duchess that he loves another. He also discloses his real name and position to Luisa and her father. The Count interrupts this interview between the lovers. Enraged at his son's persistence in preferring a union with Luisa, he calls in the guard and is about to consign her and her father to prison, when he is, for the moment, deterred and appalled by Rodolfo's threat to reveal that the Count, aided by Wurm, assassinated his predecessor, in order to obtain possession of the title and estates.
Luisa's father has been seized and imprisoned by the Count's order. She, to save his life, consents, at the instigation of Wurm, to write a letter in which she states that she had never really loved Rodolfo, but only encouraged him on account of his rank and fortune, of which she was always aware; and finally offering to fly with Wurm. This letter, as the Count and his steward have arranged, falls into the hands of Rodolfo, who, enraged by the supposed treachery of the woman he loves, consents to marry the Duchess, but ultimately resolves to kill Luisa and himself.
Luisa also has determined to put an end to her existence. Rodolfo enters her home in the absence of Miller, and, after extracting from Luisa's own lips the avowal that she did write the letter, he pours poison into a cup. She unwittingly offers it to him to quench his thirst. Afterwards, at his request, she tastes it herself. She had sworn to Wurm that she would never reveal the fact of the compulsion under which she had written the letter, but feeling herself released from her oath by fast approaching death, she confesses the truth to Rodolfo. The lovers die in the presence of their horror-stricken parents.
The principal musical numbers include Luisa's graceful and brilliant solo in the first act—"Lo vidi, e'l primo palpito" (I saw him and my beating heart). Besides there is Old Miller's air, "Sacra la scelta è d'un consorte" (Firm are the links that are forged at the altar), a broad and beautiful melody, which, were the opera better known, would be included in most of the operatic anthologies for bass.
There also should be mentioned Luisa's air in the last act, "La tomba è un letto sparso di fiori" (The tomb a couch is, covered with roses).