Rookie detective Antoine Derouère (Jalil Lespert) accepts a position with Paris's elite homicide division, where his first days as a new lieutenant are routine. But when the body of a drifter is found on the banks of the Seine, the entire squad is thrown into turmoil. Led by a recovering alcoholic unit commander (Nathalie Baye), Antoine and the seasoned investigative team unravel a case of shocking violence that will change their lives forever.