Padua, 1540. Angelo is married to Caterina but has an affair with Tisbe, an actress who travels with Rodolfo, presented as her brother but actually her lover and also Caterina's first and true love. Tisbe is also searching for the daughter of the woman who saved her mother from capital punishment and to whom she had given a crucifix. Caterina, victim of a plot hatched by Angelo and Tisbe, is saved by her at the last minute, as she recognizes her as the daughter of the woman who saved her mother from capital punishment.