Parisian private investigator Aimée Leduc doesn't know that her life is about to be upended. Her ex, Melac, has been hounding her to move their daughter, Chloé, to Brittany. Aimée is fed up with his threats to take her to court and has stopped answering his calls. Which is why she doesn't know he's waiting for her by the Bassin de la Villette as she leaves a client's office late one night. When she finds him there, bleeding in the canal, he has just been stabbed by an assailant, who knocks Aimée unconscious and plants the bloody knife in her hands.

Now Aimée is in police custody, debilitated by a concussion, with overwhelming evidence pointing to her as Melac's killer. She must figure out who murdered Melac--not an easy job, given the target on his back as a former homicide investigator. Cut off from her typical network and forced to operate under multiple layers of cover, Aimée must go deep into the underbelly of Paris's 19th arrondissement, where she rubs shoulders with biker gangs, paranoid journalists, grieving parents, and frustratingly tight-lipped ex-cops on her hunt for justice.