The Bay of Naples. Sisters Fiordiligi and Dorabella are engaged to Guglielmo and Ferrando. The men trust their fiancées’ faithfulness implicitly but Don Alfonso thinks otherwise and plans to prove it. A wager is made. Don Alfonso tells the sisters that their sweethearts are to be sent away with their regiment. A tearful farewell follows.
Soon afterwards, Don Alfonso introduces the men – disguised as ‘Albanians’ – to the sisters. Having been rejected, the men take ‘poison’ and fall to the ground. Despina, the sisters’ maid, in on the deception, brings them back to life with a giant magnet, but the women still don’t succumb. Despina suggests a little light flirting to the women. Each sister eventually falls for the other’s fiancé. The men are furious.
Don Alfonso tells them he knew this would happen – women are like that. At the betrothal party, news arrives that Ferrando and Guglielmo are on their way back. The ‘Albanians’ disappear, returning out of disguise. The truth is revealed. The sisters are forgiven. Don Alfonso collects his winnings .