Sterenn decides to cover up the manslaughter of his son by drawing inspiration from the modus operandi of the killer who rages in the region. At the same time, she is continuing her investigation in collaboration with Lyes Bouaouni, from the Lyon PJ.

Matteo, Jeremy's boss, has just been kidnapped by the killer. A race against time begins to save him. Faced with the killer, Sterenn tries to convince him to spare Matteo... in vain. Arrested, the killer refuses to speak. Except on Sterenn, on whom he imposes a diabolical pact...