In the underbelly of the Parisian criminal world, the Police are frustrated by a gang committing a series of violent robberies. Leo Vrinks and Denis Klein are two cops seeking promotion, and the imminent departure of the Chief sets the scene for them to compete for the vacant throne. The competition between them becomes increasingly ruthless and blurs the usual lines of morality, until there seems no difference between the police and the criminals they chase. Vrinks, meeting with a source, becomes involved with a murder. Klein seizes the opportunity to up the ante and arranges for the arrest of Vrinks, but when he goes further and viciously involves Vrinks' wife, Camille, revenge is inevitable.

Following a breakdown, multi-lingual Jean quits his job as a UNESCO translator to become handyman at Emilie's hair salon. Smitten by her he writes her a love letter but she thinks it comes from an elderly admirer and sends it on to her mother Maddy, who needs cheering after her husband left. Eventually Maddy comes to the conclusion that Jean is her secret admirer and Emilie plays up to this to keep her mother content and sane. When Emile tells the truth neither Maddy or Jean are pleased but love eventually finds a way to make them all happy.

After a successful mission against drug lords, the efficient Captain Damien Tomaso is framed at home with three kilograms of heroin planted by the police in his kitchen and he is arrested. Meanwhile a group of teenagers film the action of dirty agents leaded by Roland from the security agency executing policemen in their car and then leaving the car with the corpses in the 13th District to blame the gangs and begin a civil war. Behind these events, the corrupt chief of the security agency Walter Gassman had received a huge amount as kickback from the constructor Harriburton that has interest to construct buildings in the poor area and uses the situation to force the President of France to authorize to nuke five towers in the district. The teenager with the film is hunted by the police but he delivers the memory card to Leito meanwhile Damien calls him from the precinct asking for help. The...