Gamache returns to Three Pines to investigate the disappearance of the popular resident Marc Fortier but it soon becomes a murder case that leads Gamache and his team into the heart of the village’s dark past at St Anthony’s. Meanwhile, Lacoste discovers a key piece of evidence relating to Blue’s disappearance has been faked, and with Gamache’s encouragement secretly reopens the case.

The villagers confront the truth of their past and exorcise their collective demons as Gamache makes a breakthrough in the murder case and realises Marc’s killer had a very personal motive. Meanwhile, Lacoste makes a discovery relating to Blue’s disappearance that seems to identify a key suspect.