ACT I: When the curtain rises, the field Marshal's wife "Marschallin" has just spent the night with her 17-year-old young lover, the handsome Count Octavian. Their breakfast is interrupted by the visit of the Baron Ochs von Lerchenau, the Marschallin's cousin. He has come to ask her advice regarding the naming of the Knight of the Rose (Rosenkavalier) - a custom whereby a silver rose is presented to the woman he has chosen to marry. In this case he has chosen Sophie, the daughter of the newly wealthy Herr von Faninal. Afraid of being caught by the Marshal himself, Octavian hurriedly disguises himself as a chambermaid (Mariandel), with whom Ochs flirts outrageously. The Marschallin, following her morning rituals, remembers herself as a young unsuspecting girl, just like Sophie, and ponders the reality of her affair with Octavian who will inevitably move on to a younger woman. She decides to give the silver rose to Octavian, who will know what to do with it.
ACT II: In Herr von Faninal's palatial home, Sophie, Faninal and her Duenna are awaiting the rosebearer's arrival. Octavian ceremoniously presents her with the rose, and they are mutually attracted at first sight. Ochs is ushered in and fondles Sophie lecherously. Sophie is appalled, and Octavian vows to prevent the marriage. Octavian challenges Ochs to a duel and wounds him slightly. Ochs acts as if he has been severely injured, and Sophie tells Faninal she refuses to marry this oaf. While Ochs is left alone, he receives a message from Marschallin's chambermaid, "Mariandel", agreeing to a meeting. Ochs is delighted.
ACT III: Octavian rehearses the opening of trapdoors and other devices with which he plans to scare Ochs. The Baron meets "Mariandel" for supper, and tries in vain to seduce the "girl". Every time he approaches her, apparitions appear at windows or through trap doors. Ochs calls the police and tells the suspicious commissioner that he is dining with his fiancee, Sophie. Octavian has Faninal and Sophie sent for, the truth is uncovered and Octavian sheds his disguise. Meanwhile the Marschallin enters and assures the commissioner that all was but a masquerade. Ochs leaves, persued by many. The young lovers sing of their delight, and Marschallin accepts the situation in good grace.
