In the shadowy world between right and wrong, John Mercer is a modern-day gun for hire, beholden to his sinister master but not the boundaries - moral or otherwise - of the law. Released from prison unexpectedly early, Mercer is introduced to Kenny Jameson, a police officer 'retired on grounds of ill health.' Jameson makes it clear to Mercer that his freedom comes at a price; he must remove an untouchable criminal who has recently dispatched a senior police officer to an early grave. Mercer carries out the hit but finds that the promise of freedom was illusory. Jameson had no intention of agreeing to his real liberty. Thrust together with the deviant Calum and the beautiful but amoral Rose, Mercer and his new 'friends' must bring their unique talents to bear on the fundamental mission - to disorganise crime, and bring order where the law has failed.