In the heart of Philadelphia's badlands, Homicide Detectives Byrne and Balzano are called out to a particularly chilling crime scene. Once the pillar of the neighbourhood, an abandoned church has become a killing room. At first it looks like a random act of violence. But then a second body is found, and a third. Each crime scene more disturbing than the last, each murder more brutal. And it soon becomes horrifyingly clear that a cold, calculating and terrifyingly precise mind is at work.