January 1973: In the middle of Glasgow, a teenager shoots a young woman in broad daylight on the street before turning the gun on himself. Detective Harry McCoy, who was warned about the murder the day before by a psychotic inmate in prison, is faced with a mystery. Especially since the inmate himself is killed. McCoy uses his old connections to Glasgow's underworld to make progress in the investigation, but he quickly finds himself at odds with the Dunlops, the most powerful family in the city. His boss also tries to rein him in. But McCoy remains undeterred.