To every action there is always an equal and opposite reaction and Doctor Lawrence Cassler understands this better than most.
Lawrence Cassler is a kind, intelligent gentlemen who works passionately as a veterinarian. In his moon lit hours Lawrence is a sociopathic serial killer that has a complete lack of empathy towards the lives of people that are cruel to animals. Driven by the hate for his abusive step father and by the morale understanding that you reap what you sow, Lawrence utilizes his organisations database to locate people associated with animal cruelty, and then murders them in the way he deems equal to the cruelty they have committed.
Lawrence managers his double life exceedingly well, but his idle is disrupted when a cold case is re-opened and the NZSIS are hunting him for the cruel and grotesque murder of his abusive step father. Lawrence knows he does not make mistakes, and that no mind is capable of tracing his steps, he knows someone is working behind the scenes and he is determined to ensure they reap what they have sown.
The SIS figured this to be a straight forward operation, what they didn't realise was there is a difference between catching a killer, and outwitting the devil.