When an intricate old map is found stuffed into the walls of the bistro in Three Pines, at first it seems no more than a curiosity. But the closer the villagers look, the stranger it becomes. Given to Armand Gamache as a gift the first day of his new job, the map eventually leads him to shattering secrets. It leads the former Chief of Homicide for the Sûreté du Québec to places even he is afraid to go but must. There he finds four young cadets in the Sûreté academy, along with a dead professor. And, with the body, a copy of the old, odd map. The focus of the investigation soon turns to Gamache himself, his mysterious relationship with one of the cadets, and his possible involvement in the crime.