Victor is a free-lance contract murderer. He works solely for money. He has previously worked for the CIA and for British Intelligence. He meets a British Intelligence agent who gives him a contract to murder a Serbian gangster for no particular reason. Victor murders the British Intelligence agent because British Intelligence are paying to get rid of a corrupt agent. The British Intelligence agent has sold Victor's details to an unknown enemy who has placed a bounty on Victor's head. Victor is attacked by a male free-lance contract murderer whom he fights to a stand still but does not kill. Victor is seduced by a different free-lance contract murderer whom he kills after having sex with her. British Intelligence confirm they want Viktor to kill the Serbian gangster. Victor joins the Serbian gangster's gang, getting a couple of innocent trafficked women killed in the process. Viktor gets into a fight with various envious members of the Serbian gang and kills them. The male free-lance murderer from earlier catches up with Viktor, they fight, and Viktor kills him. The Serbian gangster has another innocent trafficked woman murdered. Viktor murders the Serbian gangster. British Intelligence approves of Viktor's actions. Viktor murders another Serbian gangster who is recovering in hospital from being shot by Viktor. End of Story.
You have just saved yourself from reading 439 boring pages. The characters are all flat with no depth. There are scenes of unconvincing extreme violence. There is no real motive developed except "someone is attacking me so I kill them". The book does not feel like part of a series although the author has apparently written other books with the same character there is absolutely no development.