After a number of years working for a British clandestine organisation as an operative licensed to kill Brad Spelling has finally decided to call time on his employment and in his own words wants to live a normal life without looking down the barrel of a sniper's rifle. After his last operation in Turkey he tries to hand in his resignation which is partially accepted by his mentor but only on the proviso that he will reassess his options in six months time when, if he then still wants to go nobody would stand in his way. Although adamant that he will not change his mind Spelling has to agree to the terms but starts to make plans for a future which includes caring for his sister who has been in a coma since a car crash in which their mother was killed. Then a mysterious letter arrives from a firm of solicitors advising that he is the sole beneficiary to the estate of the late Thomas Catt ... a man he does not know and has never heard of. As the solicitors are adamant they have made no mistake he visits their offices and realises that the enigmatic Catt is actually an alias for Jimmy Holt, who with his own step-father had been undercover police trying to bring down the Johnson brothers, a notorious crime family based in London. A few years earlier both men had reportedly been killed in what had been classified as separate motoring accidents. Apart from the financial aspect of the estate Holt left a number of documents and testimonies alleging that Spelling's relative was actually killed on the instructions of the Johnsons and that he had been forced to stage his own death in order to try and gain revenge but had not been able to. From the grave he states that he knows that Spelling is the ideal person to take over from him, citing the need for revenge not only for his family but also for the many others who had suffered at the hands of the brothers. He is advised that he would not be acting alone and would be contacted anonymously by someone who would make themselves known by using the codename Pi. Learning that the death of his step-father had been a deliberate murder Spelling decides to find the killer. Unable to tell anybody what he is doing, not knowing who to trust, he is forced to seek out those responsible discovering that people are not all that they seem, that truth is easily corrupted and there is a fine line between honesty and deceit as well as between friendship and hatred. Along the way he learns that friends and enemies are not always clearly defined and can be one of the same and the identity of his step-father's murderer comes as a complete surprise. After completing what Holt had asked of him there is still one final mystery that remains ....who is Pi?