When Detective Inspector Andy Harris catches serial killer Kevin Mackie, who then takes his own life whilst awaiting trial, he believes his job is done and he can get on with his life. But, shortly afterwards, he is the victim of an acid attack by an unknown assailant. Scarred for life, Andy is reinventing himself as a university lecturer in criminology. But he is called back into work to investigate another murder, bearing all the hallmarks of Mackie's crimes. Is it a copycat killing or did Andy arrest the wrong man? As he is forced to revisit the old cases, he has to face the fact that when the ghosts of the past come back to haunt you, they may not be ghosts at all.