Told in reverse, the show follows DCI Gabriel Markham and his team as they try to hunt down a serial killer.
Gabriel comes face to face with the prime suspect, but his deep and personal connection to the case could see him jeopardizing his career. As a dangerous game of cat and mouse ramps up to a shocking climax, Gabriel begins to lose control.
Gabriel and the team are dealing with the fact that another body has been discovered, seemingly the work of the serial killer.
When Gabriel publicly denounces the acid murderer during a press conference, the killer's sights turn towards him and the tension ratchets up as the hunter becomes the hunted.
The story of the acid murderer's first victim is revealed, as another suspect enters the frame. Gabriel receives some help in his investigation from an unexpected source - but is the situation more complex than it seems? As Gabriel indulges in reckless, self-destructive behaviour that could jeopardise everything, he is blind to the possible consequences of the life that he is leading. The casual cruelty of Gabriel's vanity is exposed, and his relationships come under more strain. Meanwhile, the team have to face up to the fact that they have a serial killer on the loose and begin the hunt in earnest. As Gabriel sets his sights on tracking down the first suspect, Elaine makes a difficult decision to revisit her past. Finally, while tracing the journey of the first victim's final steps, the identity of the killer is unmasked.
Following Gabriel's discovery of a crucial piece of evidence, the hunt is on to track down the killer as the truth is finally pieced together. With the net tightening, a thrilling chase of twists and turns ensues, and as Gabriel begins to piece together the trail of violence leading to the killer, he ends up putting everything he holds dear at risk.
