To survive the violent streets of Belfast in the 1970s, young Darren McCann learns to fight. The IRA are interested in recruiting him but, though he is a Catholic, he refuses to take sides until a family tragedy allies him with "the cause". His specialist training turns him into an efficient sniper and covert operative. One brutal interrogation earns Darren the reputation as "The Butcher of Belfast" and pairs him with his infamous knife, The Killer. After a high profile assassination, he takes refuge in Spain where he works with ETA terrorists and takes part in an audacious bank raid. He returns to Ireland to continue the fight, but the seeds of doubt are planted in his mind by a British MI6 officer with shocking information and plans to turn him into a double-agent.