Detective Anna Manni (Argento) travels to Florence on the trail of a serial killer, Alfredo Grossi (Thomas Kretschmann). While visiting a museum, Anna is overcome by Stendhal syndrome, a condition which causes the sufferer to become overwhelmed when viewing great works of art. When Alfredo learns of Anna's disorder, he uses it to disable her before he kidnaps her and subjects her to a brutal and sadistic sexual attack. Although she manages to escape, Anna is left deeply psychological trauma. Alfredo continues to track her movements and is able to capture her again. This time, however, Anna turns the tables on her abductor, breaking free of his grasp, badly wounding him in the process, and knocking him into a river.