DCI Gabriel Markham's life becomes intrinsically bound to that of a suspected serial killer.
Gabriel comes face to face with the prime suspect in the serial murders.
Gabriel deals with the discovery of another possible victim of the acid-attack serial killer.
With pressure mounting from all sides, the killer's sights turn towards Gabriel.
As the investigation gets a helping hand, the story of the acid murderer's first victim is revealed.
Following Gabriel's discovery of a piece of evidence, the hunt is on to track down the killer.