Yann starts to talk and the investigation partially advances. But that is enough to cause a separation with his boyfriend Lucas and a definitive break with his foster mother. Hélène sees her family shattered, and she also lives a professional humiliation: a young divisional commissioner, Ronan Berg, is now in charge of her investigation, and very interested in the latest developments. What she does not know is that the ambitious Berg is "Lancelot", the man she is tracking. This elusive and methodical killer seeks to eliminate Yann and Lucas.