A room in Eisenstein's villa. Alfred serenades Rosalinde through an open window as Adele enters the room, reading a letter from her sister Ida. There is an elegant party at Prince Orlofsky's palace that evening, which promises to be quite entertaining. Ida encourages Adele to get the night off and borrow one of her employer's ball gowns -- she won't miss it. Unfortunately, Rosalinde denies her request.
Eisenstein complains to his lawyer, Blind, about the poor job he has done on an appeal, and the conversation becomes heated. Eisenstein had received a five-day prison term for insulting an official -- while trying to get the sentence dismissed, Blind instead caused it to be increased to eight. Eisenstein must report to the jail that very evening.
Falke pays a visit and privately tells Eisenstein about Orlofsky's party. He must enjoy one last night of fun before reporting to the prison. Falke suggests his friend adopt a false identity so that he will be able to easily mix among the guests and flirt with the young ladies. Eisenstein agrees, but his wife must not know. As he departs for “prison,” Rosalinde questions his evening attire, then feigns distress at being parted from her husband, realizing that she can now be alone with Alfred. Adele is given the evening off after all.
Dressed in Eisenstein's smoking jacket, Alfred enjoys a glass of champagne with Rosalinde, and together they profess their mutual affection. A knock at the door reveals Frank, the prison governor, who has come to collect Eisenstein -- surely he must be the comfortably dressed man before him. Not wanting her reputation to be compromised, Rosalinde convinces Alfred that he must pretend to be her husband, and he agrees to go with governor, provided she gives him a parting kiss.
Prince Orlofsky's palace The party guests praise Orlofsky's excellent hospitality. The prince requires that all enjoy themselves in his house rather than share his fate -- to be perpetually bored -- otherwise out the door they go. Orlofsky, Falke and Adele joke over how Eisenstein (disguised as a French marquis) has mistaken Adele for a lady's maid. Posing as an actress, Adele laughs it off -- she is far too pretty and petite for such low labor.
Rosalinde has received a message that she should attend Orlofsky's party. She is annoyed to see her husband ogling the finer features of her maid (who just happens to be wearing one of her best dresses). As she is masked as a Hungarian countess, Rosalinde decides to test her husband's constancy by flirting with him. She asks him to count her heartbeats by the ticking of his watch and then appropriates the timepiece for future proof of his infidelity. Eisenstein is flustered by this action, but responds to her affections. Meanwhile, Frank the governor has arrived, posing as the Chevalier Chagrin. Trapped by the nature of their false identities, he and Eisenstein attempt to hold a conversation in poorly articulated French. Rosalinde's true identity is also called into question, but she is defended by Orlofsky. To convince everyone of her masquerade, she sings a Csárdás, a folk song of Hungary.
The evening is ripe for revenge. Falke tells the prince of a masked ball he and Eisenstein attended, Eisenstein as a butterfly and Falke as a bat. In an inebriated state, Falke trusted his friend to get him home -- instead he woke up the next morning in the park where Eisenstein had left him and was forced to walk home in broad daylight, wearing his silly bat costume. Falke looks forward to paying his friend back in kind and has orchestrated the entire evening to do just that. With the party in full swing, Orlofsky calls for a toast and the majesty of champagne is celebrated by all.
Falke encourages the guests to pair off, and everyone begins to waltz. The clock strikes six o'clock, and both Eisenstein and Frank realize they must report to the prison at once.
The prison governor's office Alfred sings in his prison cell, to the ire of Frosch the jailor, who has been nipping at his boss's cognac in his absence. Frank arrives for work, still a little tipsy from the all-night party. Adele and Ida soon appear. Adele admits to her deception of the night before, but hopes Frank, still believing him to be a French chevalier, will have the right connections to get her to the stage. She gives a display of talents.
Frosch announces that a certain Marquis Renard has arrived, and the two girls scuttle into the adjoining room. Eisenstein enters, ready to serve his sentence, but is told that he is already in his cell and has asked for a lawyer. Blind arrives presently, and as Frank leaves the room to fetch the prisoner, Eisenstein demands his lawyer lend him his robe, wig and spectacles, so that he may determine exactly what is going on.
Rosalinde enters belatedly, fearful that her husband will arrive for his prison sentence and discover Alfred in his robe. Impersonating his attorney, Eisenstein observes the situation with quite rage, and offers Alfred his legal services. Rosalinde and Alfred confess their harmless rendezvous, knowing how angry Eisenstein would be if he were to find out. Rosalinde furiously declares that her husband is equally guilty, for she observed him at a party last night cavorting with women. Eisenstein reveals his identity and both spouses demand justice for their respective betrayals, for Rosalinde draws out the watch she took from him the previous evening.
All parties enter and admit their roles in the ruse -- Falke has had the “bat's revenge.” Eisenstein begs to be forgiven and all agree King Champagne the First is to blame for their foibles.
Courtesy of Minnesota Opera