A series of shootings by a lone sniper leaves Glasgow terrorised and the media in a frenzy. Who is behind the executions of some of the most notorious criminals in the city? As more deaths occur - including those of police officers and innocent members of the public - the authorities realise they have a vigilante on their hands. Police photographer Tony Winter has seen more than his fair share of dead bodies. So when he notices something in one of his negatives that the forensic team has missed - something that seems to link the sniper's victims with the case of a badly beaten schoolboy - he launches an investigation of his own. Meanwhile, DS Rachel Narey is smarting after being transferred from the sniper case onto a seemingly routine enquiry into the death of a prostitute. But she can't help but notice how every lead draws her back to the sniper. As Winter and Narey delve deeper, their quest for the truth and search for the killers will lead them both down increasingly dark and dangerous paths.