The action takes place in Germany in the 18th century, at the court of one of the German dukes.

The son of President von Walter is in love with the daughter of a simple musician, Louise Miller. Her father does not trust this, since the marriage of an aristocrat with a bourgeois is impossible. The president’s secretary, Wurm, also claims to be in Louise’s hand, he has been visiting the Millers' house for a long time, but the girl does not feel any feelings for him. The musician himself understands that Wurm is a more suitable part for Louise, although he does not like Miller, but the daughter has the last word here, her father is not going to force her to marry anyone, Wurm informs the president about the fascination of his son with the daughter of the tradesman Miller. Von Walter does not take it seriously. A fleeting feeling, perhaps even the birth of a healthy side grandson - all this is not news in the noble world. For his son, Mr. President has a different fate. He wants to marry him to Lady Milford, the duke's favorite, in order to be able to seize the duke's trust through her. The news of the secretary makes von Walter accelerate the course of events: the son should know immediately about his upcoming marriage.

Ferdinand returns home. Father is trying to talk with him about his future. Now he is twenty years old, and he is already in the rank of major. If he continues to obey his father, then he will have a place in the neighborhood of the throne. Now the son should marry Lady Milford, which will finally strengthen his position at court. Major von Walter rejects his father’s proposal to marry a “privileged charming woman”, he is disgusted by the president’s affairs and how he “manages them” at the duke’s court. The place near the throne does not appeal to him. Then the president proposes Ferdinand to marry Countess Ostheim, who from their circle, but at the same time did not discredit herself with a bad reputation. The young man again disagrees, it turns out he does not like the countess. Trying to break the stubbornness of his son, von Walter orders him to visit Lady Milford, the news of his upcoming marriage with which is already spread throughout the city.

Ferdinand bursts into Lady Milford's house. He accuses her of wanting to dishonor him by marrying him. Then Emilia, who is secretly in love with the major, tells him the story of her life. The hereditary Duchess of Norfolk, she was forced to flee England, leaving all her fortune there. She has no relatives left. The duke took advantage of her youth and inexperience and turned into his dear toy. Ferdinand repents of his rudeness, but tells her that he is not able to marry her, because he loves the daughter of the musician Louise Miller. Emilia’s plans for personal happiness are crumbling. “You are ruining yourself, me and another third person,” she tells the major. Lady Milford cannot refuse to marry Ferdinand, since she “cannot wash away the shame” if the duke’s subject rejects her, so the burden of the struggle rests with the major.

President von Walter is at the musician's house. He is trying to humiliate Louise by calling her a corrupt girl who deftly lured the nobleman's son into her nets. However, having coped with the first excitement, the musician and his daughter hold on to dignity, they are not ashamed of their origin. Miller, in response to the intimidation of von Walter, even points to the door. Then the president wants to arrest Louise and her mother and confine them to a pillory, and throw the musician himself in prison. Arriving in time on time Ferdinand with a sword protects his beloved, he injures the police, but this does not help. He has no choice but to resort to the “devilish means”, he whispers in his father’s ear that he will tell the whole capital how he removed his predecessor. Terrified, the President leaves Miller’s house.

The way out of this situation is suggested to him by the insidious secretary Wurm. He offers to play on Ferdinand’s jealousy, tossing him a note written by Louise to a fictional lover. This should persuade his son to marry Lady Milford. The president persuaded Louise's fake lover to become Hoffmarshal von Kalba, who, together with him, wrote fake letters and reports to remove his predecessor from his post.

Wurm goes to Louise. He informs her that her father is in prison and he faces the criminal process, and his mother is in the workhouse. An obedient daughter can release them if she writes a letter under the dictation of Wurm, and also takes the oath to recognize this letter as voluntary. Louise agrees. The letter, "lost" by von Kalbom, falls into Ferdinand’s hands, he challenges the marshal to a duel. The cowardly von Kalb tries to explain everything to the major, but passion prevents him from hearing a frank confession.

Meanwhile, Lady Milford arranges a meeting with Louise in her house. She wanted to humiliate the girl by offering her the place of a chambermaid. But the musician’s daughter is so noble in relation to her rival that the humiliated Emilia leaves the city. She flees to England, distributing all her possessions to her servants.

Having survived so much in recent days, Louise wants to end her life, but her old father returns home. With tears, he manages to dissuade his daughter from a terrible act, Ferdinand appears. He shows Louise a letter. Miller's daughter does not deny that it was written by her hand. The major is beside himself, he asks Louise to bring him lemonade, the musician sends to President von Walter with a request to send him a letter and say that he will not come to dinner. Left alone with his beloved, Ferdinand quietly adds poison to the lemonade, drinks it himself and gives a terrible potion to Louise. The impending death removes the seal of the oath from the lips of Louise, and she confesses that she wrote a note on the orders of the president to save her father from prison. Ferdinand is horrified, Louise is dying.

Von Walter and old Miller run into the room. Ferdinand accuses his father of the death of an innocent girl, he points to Wurm. Police appear, Wurma is arrested, but he does not intend to take all the blame. Ferdinand dies, before his death, he forgives his father.