Act I Alfred sings a serenade to Rosalinde, but it is Adele who hears it. Adele, intends to go to Prince Orlofsky’s ball and invents a story about an ailing aunt. Eisenstein, who should be departing for prison, goes instead to the ball. Rosalinde is counting on spending the evening with Alfred — but the latter, mistaken for Eisenstein, is taken off to prison.
Act II The cream of society gathers at the ball: Orlofsky is bored, but Falke promises to liven things up by a practical joke; Adele pretends to be an actress, Eisenstein — a French Marquis. A mysterious Hungarian countess keeps her mask on the whole time and therefore no one recognizes her as Rosalinde. The champagne flows, the guests make merry.
Act III Alfred sings an aria while waiting for a lawyer. Adele demonstrates her acting skills to Frank. Finding his place at prison already occupied, Eisenstein gives himself out to be the lawyer. In answer to her husband’s accusations that she has deceived him, Rosalinde confronts him with the watch, presented by Eisenstein to the ’Hungarian countess’. Orlofsky reveals his true identity, Falke delights in the fact his friend has been made to look a fool. All are forgiven — it is the champagne which is at fault!