Nounours is the nickname of a "cousin" an informer with a special arrangement with the police: he gets 10% of the drugs seized thanks to his help. When his personal contact, inspector Maurin, commits suicide, inspector GÃ©rard Delvaux takes over. Meanwhile, judge Lambert is uncovering the illegal practices of the policemen. Her persistent investigations, which had cornered Maurin, are leading to GÃ©rard, and also to Nounours as the source of heroin that led to recent cases of deadly overdoses. Nounours promises GÃ©rard increasingly bigger catches which he is intent on realising before he is forced to reveal who Nounours is to judge Lambert.