The police inspector in this movie (Michel Constantin) gets in over his head when he arranges to impersonate the (dead) relative of a drug lord. The dead man's wife and child do not take too kindly to his presence, and make his life miserable. What began as a simple sting operation becomes the focus of international attention by American drug agencies, the American Mafia, other local drug rings, and European police circles. Complicating matters are the attentions of other French police factions. The bad guys almost have their way, until they threaten the inspector's adopted family.
Source : allmovie.com