A sinner is a story of love and jealousy, set in a Sicilian village, Vizzini, in the late nineteenth century and published in 1865.
A young man from Catania, Peter, a law student who loves literature, falls madly in love with a woman he met during a walk to the city's public gardens.
The woman is Narcisa Valderi, the Earl of Prato’s wife; the young man courts her and she seems glad about it. The man writes a drama, Gilberto, which immediately makes him famous.
Thanks to his success the woman fell in love with him. But after a very short period of happiness Narcisa, who has become aware that the young man begins to tire of her obsessive and unrestrained love, she commits suicide. Peter, who cannot recover, will spend the rest of his life in a mediocre way.