11-year-old Louison is on vacation by the sea. One evening, the boy she has fallen for offers her a walk on the beach. But the romantic escapade she was hoping for soon turns out to be a pretext for forcing sexual contact on her.

The body of a real estate developer and candidate for mayor of Bordeaux is found murdered in his home according to a ritual reserved, two centuries earlier, for runaway black slaves. Discovered by his closest friends, all, like the victim, from prominent Bordeaux families with a troubled past during the slave trade. On the spot, Clémence Lacoste, a police captain accustomed to the field and a native Bordelais, is forced to team up with Lieutenant Antoine Rosy, an elegant Parisian more accustomed to the office than the field... To find the killer and stop this series of murders, our two heroes are going to uncover buried elements of Bordeaux's history... but above all of their own past and origins.