It is 1969 and Glasgow is in the grip of the worst winter in decades, yet it is something else that has Glaswegians on edge: a serial killer whose name alone is enough to make them tremble with fear. The Quaker has killed another victim, snatching a young woman from a nightclub and dumping her body like trash in the back of a cold-water tenement. He leaves no clues, and the investigation has led police down one blind alley after another.

DI McCormack has few friends in his adopted city and a lot to prove. A talented young detective from the Highlands, an outsider with troubling secrets of his own, Duncan McCormack is brought into the investigation to identify where, exactly, it's gone wrong. His arrival is met with anger and distrust by cops who are desperate to nail a suspect. When they identify a petty thief as the man seen leaving the building where the Quaker's last victim was found, they decide they've found their serial killer. But McCormack isn't convinced. From ruined backstreets, to deserted public parks, and down into the dark heart of Glasgow, McCormack follows a trail of secrets that will change the city—and his life—forever.