Northern Italy is under Austrian rule in the late 1850s. Lorenzo Croce, an official of Milan, sees for the first time Francesca, the daughter of Martini, a Milanese silk fabrics merchant. She is protesting to Major Karlheinz Berger of the Austrian army's intelligence bureau about a recent order. The headquarters of the Austrian army has suspended the business of her family due to a suspicion that her elder brother Pietro is a member of an anti-Austrian group. Lorenzo is ordered by his superior to investigate Pietro.
