A young woman is assaulted and left for dead while walking the Yorkshire moors. A local man is found murdered on the edge of a landfill site. But what do these seemingly unconnected crimes have something in common? Forensic profiler Jo McCready is brought in by DCI Callum Ferguson to find out. Were the victims led to their deaths by the mysterious lights flickering above the bogs? But Jo has a secret. Local gangster and prison inmate, Chris McGarry, knows the dead man and wants revenge. He also has leverage on Jo, and as the investigation intensifies, he presses her to pass on police information. Jo must tread carefully. Will she follow the light - or step into the dark?