Paris, 1991. The true story of Franck Magne, a young inspector starting out in the Criminal Investigation Department at 36 quai des Orfèvres, in the Crime Squad. His first case deals with the murder of a young woman. His investigation leads him to study similar cases that he’s the only one to link together. He’s quickly confronted by the reality of police investigation work: the lack of equipment, bureaucracy... For 8 years, obsessed by this investigation, he’ll hunt the serial killer that no one else believes exists.