Police commissioner Herville is found dead in a Chinese restaurant in the 13th arrondissement of Paris. Gilou must break the news to Laure, who is being treated in a Police rehabilitation center. Now in charge of the unit, Gilou begins investigating with Ali, a young cop, fresh out of training. They quickly find themselves on the case of a break-in gone wrong and the trail of 15-year-old Ryan, a juvenile delinquent. Roban learns he must soon retire but still manages to oversee the Herville case. Awaiting trail, Joséphine struggles with life in prison....