John Mercer is ex-Special Forces serving a double life sentence for the murder of his aunt and uncle. It was a crime he committed out of revenge for the years of physical abuse his sister Jess suffered at their hands.
Released from prison unexpectedly early, John is introduced to the shadowy Lenny Jameson, a police officer retired on grounds of “ill health.”
He quickly learns that his freedom comes at a price. Jameson runs an unofficial operation with a simple brief: remove untouchable criminals and disorganise crime. Mercer’s role is that of hitman.
Blackmailed by Douglas into killing for the state, Mercer struggles to come to terms with his mission. Desperate for any chance at a normal life, he attempts to reconcile himself to the task in hand. But each new assignment only brings him further and further into conflict with his taskmasters and his conscience begins to take over.
To help him on each hit, Mercer is introduced to his new colleagues. They include Calum McKenzie, a petty thief, whose main interests are girls, drugs and music. He is worlds away from the intelligent, thoughtful ex-soldier.
Things are further complicated by the final member of Lenny’s group of misfits: the beautiful but duplicitous Rose (Tamzin Outhwaite). A disgraced ex-copper who has always used her sexuality and guile as her primary weapon, she is more than a match for Mercer.