Tony comes under scrutiny from both the police and the media when it is revealed that he made a serious error of judgement in a case over ten years ago, which resulted in the conviction of an innocent man for a series of murders. As each and every one of his cases is torn apart, he realises he must find the real killer in order to prevent him from losing the one thing he holds dear.

Tony and Alex investigate a serial killer who leaves behind a trail of two bodies at every crime scene. Tony suspects that the murderer may have a link to religious zealotry, but struggles to see beyond his own lack of personal faith and religious disinterest. When Alex discovers the killings may be related to a disparate group intent on cleansing the human race, Tony is forced to see the light to crack the case.

Tony and Alex investigate the violent murder of a young prostitute, but find that their prime suspect for the murder was incarcerated in a high security psychiatric unit at the time. Suspecting a link to an ongoing Vice operation, Alex teams up with squad detectives Shields & Mulligan. But when the next target becomes one of their own, Tony is forced to find the link between the killer and the outside world.

Tony is forced to face up to his past demons once more when evidence that he submitted against a murder suspect is torn apart by his legal team. Tony's world is rocked once more when he discovers that Carol has been replaced by a new, combative and wily detective, Alex Fielding. Although the pair take an initial disliking to one another, they soon realise they need to work together to solve a complex murder case.