Act 1

Count Siegfried leaves his wife Genoveva in the care of his faithful servant Golo while he goes off to join an army fighting a Saracen invasion. Genoveva faints as Seigfried departs, and Golo, who is secretly in love with her, takes advantage of this and kisses her, a scene witnessed by Margaretha, Golo's former nurse. Margaretha, upset by being no longer welcome at the castle, has since become a sorceress, and keen to avenge her slight, offers to help Golo woo Genoveva, and undermine her position at court.

Act 2

In her bedroom, Genoveva hears from Golo that Siegfried has been victorious and will soon return. She asks Golo to sing to her and in the course of their duet he confesses his passion. Genoveva is appalled and rebuffs his advances. Golo decides to take revenge, and on the advice of Margaretha, he manages to persuade Drago, Siegfried's steward, that if he hides in Genoveva's room, he will soon find proof that she is betraying her husband. Meanwhile, Margaretha spreads more rumours about Genoveva, and the people of the castle, egged on by Golo, go into her room. Discovering Drago there, they promptly jump to the wrong conclusion and after killing him, imprison Genoveva as an adultress.

Act 3

Siegfried has been wounded in the victory, but is being nursed by Margaretha in disguise. In this position Margaretha has not only done her best to make sure Siegfried does not recover, she has also been trying to undermine his belief in his wife's fidelity. As proof of the latter, she offers Siegfried a look into her magic mirror, which reveals past events, but he does not do this until Golo arrives, with news of Genoveva's apparent infidelity and Drago's death. A look into the mirror seemingly confirms this version of event with images of Genoveva holding out her arms to Drago, images which cause Siegfried to smash the mirror and make off with Golo back to the castle, intent now on the execution of his supposedly faithless wife. From the splinters of the boken mirror, however, Drago's image arises threatening Margaretha and bidding her reveal the deceit she has practised.

Act 4

Siegfried's soldiers have taken Genoveva to a rocky wilderness for her execution. She prays for deliverance, calling out for Siegfried, and has a vision of the Virgin Mary. Golo offers to save her, but after she rejects his advances again, he leaves her to her fate.The soldiers are about to kill Genoveva, when the sound of hunting horns comes from the forest, announcing the arrival of Siegfried and a stay of execution. From a repentant Margaretha, Siegfried has been told the truth of what really took place in his absence, and able to save Genoveva just in time, now carries her back in triumph to the castle. There, in the courtyard, the happily reunited couple are greeted by Siegfried's retinue, and blessed by the bishop.