Mozart’s Così fan tutte begins entirely in the spirit of an opera buffa:the men – Ferrando and Guglielmo – make a bet on the fidelity of their women, pretend to go to war and return in disguise. The women, their fiancées Dorabella and Fiordiligi, do not recognise the men – and embark on an affair with the supposed strangers. However, what began as a fast-paced “dramma giocoso” and a harmless joke played by the young men’s experienced friend Don Alfonso increasingly becomes a drama of existential dimensions, which ultimately wreaks havoc among all involved. InCosì fan tutte, Mozart portrays the inconsistency and complexity of human feelings as no-one else can. In Sven-Eric Bechtolf’s production, Julia Kleiter will be singing Fiordiligi at Zurich Opera for the first time, Anna Stéphany will be Dorabella, Mauro Peter débuts as Ferrando, and Ruben Drole sings Guglielmo. At the rostrum will be Karl-Heinz Steffens, who last conducted Così fan tutte at La Scala in Milan.

Act 1
The philosopher Don Alfonso and two young men enter into a debate regarding the constancy of women. Guglielmo and Ferrando are so convinced of the fidelity of their betrothed, Fiordiligi and Dorabella, that they accept Don Alfonso’s proposal to bet one hundred gold coins on their constancy. Don Alfonso intends to prove to them that their brides are like all women – faithless. His only condition is that they do his bidding for 24 hours. Guglielmo and Ferrando insouciantly accept his demands.

The sisters Fiordiligi and Dorabella await their fiancés in a state of joyful anticipation; how­ever, Don Alfonso arrives in their place to tell them – apparently dismayed – that Guglielmo and Ferrando have unexpectedly been drafted into military service. The couples have only a short time to bid farewell – perhaps forever, as the young ladies fear.

Despina pokes fun at the young women’s pain at the separation – nothing, she says, is easier than replacing a lover. Fiordiligi and Dorabella are appalled. Don Alfonso bribes Despina into helping him to gain access to the young women, and to ensure that he is heard. In exotic disguise, Guglielmo and Ferrando now attempt to make a conquest of their lovers, but are brusquely rejected. They already demand their stake from Don Alfonso, but the 24 hours have not yet passed.

Certain of success, the men again launch an attack. In front of the two sisters, who lament their fate, they claim to have poisoned themselves out of unrequited love. Disguised as a doctor, Despina revives the men, seemingly dead.

Act 2
Despina warns the girls of the inconstancy of men, and intercedes in favour of the unknown admirers. Dorabella and Fiordiligi finally allow themselves to be persuaded to agree to another meeting. They assure each other that they intend to enter into a flirtation, and rapidly agree which partner each should take. Dorabella chooses Fiordiligi’s fiancé Guglielmo, while Fior­diligi opts for Dorabella’s intended, Ferrando.

At a party organised by Don Alfonso and Despina, the two men feign timidity. Fiordiligi takes the initiative and persuades Ferrando to join her on a walk. The men find the partner swap initiated by the girls deeply unsettling. Dorabella, left alone with Guglielmo, succumbs to his advances. By contrast, Fiordiligi flees from Ferrando, although she has to admit to herself that the stranger is by no means indifferent to her.

Ferrando accepts his defeat and tells Guglielmo of Fiordiligi’s constancy; however, he has to hear from the latter that Dorabella has yielded to him. Fluctuating between fury and despe­ration, Ferrando collapses. Guglielmo, who demands his stake from Don Alfonso, has to accept being told that the experiment is not yet complete.

No longer sure of her feelings, Fiordiligi intends to follow Guglielmo to the battlefield in order to remain true to him and, if need be, to die at his side. Ferrando wants to dissuade her from her plan and goes all the way; her resistance fails. Cut to the quick, the two men think of revenge, but Alfonso, who has won his bet, recommends that they marry their fiancées, whom they do love, after all.

Fiordiligi and Dorabella are ready to enter the married state with their new lovers. Despina, disguised as a notary, presents the marriage contracts. Scarcely have the girls signed them than a march heralds the return of their former betrothed. While the men hide, Fiordiligi and Dorabella are utterly petrified. With cruel satisfaction, Ferrando and Guglielmo gradually expose the intrigue, until they reveal themselves as the exotic lovers. Despina is now also aghast, while Don Alfonso attempts to reestablish the status quo.