The setting is the estate of the beautiful and wealthy aristocrat Countess Maritza, which is managed by a man who calls himself Bela Törek. He is, in fact, Count Tassilo Endrödy-Wittenburg, who was recently forced to sell all his possessions to pay his late father’s debts. Baron Karl-Stephan Liebenberg arrives and tells Tassilo that all accounts have been settled and he owes nothing more. Tassilo tells him he plans to remain in his new job, incognito, until his sister Lisa has a proper dowry.

Maritza returns home to the estate, ostensibly to celebrate her recent engagement. She tells those assembled that her fiancé was unfortunately detained. When Tassilo introduces himself as the new manager, she treats him with condescension.

Tassilo discovers that his sister Lisa has arrived with Maritza. The two of them meet, and he tells her he has adopted this disguise as a bet with friends. She promises to keep his secret.

Meanwhile, we learn that Maritza too has a secret; she confesses to her friend Ilka that she is not really engaged. In the hope of avoiding suitors who have been after her money, she told reporters she was going to marry a Baron Zsupan – who is actually a fictional character from an operetta.

To her amazement, Baron Zsupan’s arrival is announced. She tells him there must be some mistake, but he refuses to take no for an answer. The wedding party heads off for the tavern – except for the bride-to-be and her manager, to whom she apologizes and offers her friendship.

It is four weeks later. Lisa has fallen in love with Zsupan, who also seems to be developing feelings for her. Tassilo, attempting to discuss business matters with Maritza, finds himself distracted by her beauty. Zsupan announces that he cannot marry Maritza after all, since his grandfather’s will stipulates he must marry a poor woman or risk losing his own fortune. She is relieved.

A cabaret troupe entertains. Maritza and Tassilo begin to grow closer, though she is aware that their differences in social standing make marriage unthinkable.  Maritza finds a letter of Tassilo’s and, misinterpreting it, becomes convinced that he – like so many before him – is wooing her for her fortune. Angrily, she hands him a large sum of money, which he hurls at the feet of her guests. He then storms out with Lisa, whom he refers to as his sister. Maritza suddenly understands that the dowry he talks about in the letter is Lisa’s – and, what’s more, that he really is an aristocrat. She is thrilled.

The next morning, Tassilo hands in his resignation. Maritza tries to talk him into staying, but both are too proud to speak openly of what has happened. Tassilo’s aunt, the Princess Bozena, unexpectedly arrives and tells him that, thanks to oil discovered on their property, the family is rich again. She adds that she has arranged for him to be married lo a wealthy noble­woman. He tells her that he is in love with another.

Lisa discloses lo Zsupan that she is penniless. Thrilled, he proposes marriage, and she instantly accepts. Tassilo’s aunt learns that her nephew and Maritza are in love, but too proud and stubborn lo admit it. She arranges for Maritza to disguise herself as the wealthy noblewoman, and tells Tassilo he must explain to her why he cannot go forward with the marriage contract. Tassilo goes to her and apologizes for the misunderstanding. Maritza removes her disguise and the lovers embrace.