Northern Italy in the late 1980s, and Commissario Trotti of Italy's Poliza di Stato is called to the scene of a brutal murder. When he arrives he find that the disfigured victim is an old friend, schoolteacher Rosanna Belloni. Warned off the case by his superiors, Trotti continues his enquiries - unofficially. First he must trace Rosanna's missing drug-addicted sister and before long he finds himself involved in the most complex and puzzling investigation of his career.