Romain (Lino Ventura) loses his wife in a forest fire. His son blames him for the death and leaves France for Canada. Romain is called to Canada when he is notified that his son was murdered. When the murdered man turns out to be someone else, Romain's son automatically becomes the chief suspect in the murder. Romain then goes on a dangerous search to look for his child. He searches through the byway underground and underworld life in Canadian cities with the help of Karen (Angie Dickenson), a lady with an unsavory past.