The poet Prosdocimo (baritone) is searching for a plot for a "drama buffo". He meets a band of Gypsies, including the beautiful but unhappy Zaida (mezzo-soprano) and her confidant Albazar (tenor). Perhaps the Gypsies can provide some ideas? Prosdocimo's friend, the obstinate and sometimes foolish Geronio (bass), is looking for a fortune teller to advise him on his marital problems, but the Gypsies tease him. Zaida tells Prosdocimo that she is from a Turkish harem. She and her master, Prince Selim, were in love, but jealous rivals accused her of infidelity and she had to flee for her life, accompanied by Albazar. Nevertheless, she still loves only one man and that man is Selim. Prosdocimo knows that a Turkish prince will shortly be arriving in Italy. Perhaps he can help? Geronio's capricious young wife Fiorilla (soprano) enters singing (in contrast to Zaida) of the joys of free and unfettered love. A Turkish ship arrives and the prince disembarks. It is Selim (bass) himself. Fiorilla is immediately attracted to the handsome Turk, and a romance rapidly develops. Narciso (tenor) appears in her pursuit. He is an ineffectual admirer of Fiorilla posing as a friend of her husband. Geronio follows, horrified to learn that Fiorilla is taking the Turk home to drink his coffee!