Novak (Victor Lanoux) is a police inspector to whom any means is fair in getting evidence on criminals - especially drug dealers. He is after a drug ring that includes a city official and desperately needs evidence to bring the corrupt politician to trial, and to close down the ring. To that end, he involves Helene (Marlene Jobert), the politician's secretary, causing her intensive emotional stress as he destroys her home life and unintentionally costs the life of her sister. By the time events have completed their course, the inspector has a chance to help Helene back to normalcy, and to reflect on the ultimate worth of his methods.