Suddenly appearing in Florence, an evil seductress causes Cesare, the city’s ruler, and his son to both fall madly in love with her. The son, killing his father before an order to torture the woman can be carried out, then turns the city’s churches into dens of sexual debauchery. Acts of evil and corruption continue unabated until the arrival of Death, who brings with her a horrible plague which she is about to loose upon the city.