The hunt for a serial killer who is stalking London’s West End becomes personal for Murphy when tragedy strikes at the heart of the investigation.

Parmer, a promising young police officer, has apparently committed suicide. Murphy is sent undercover to find out whether he was a victim of racist bullying.

Murphy is out posing as a criminal armourer to make an arrest. During the set-up he recognises Caz Miller, a man known for his connections to criminal gang leader and known cop-killer Dave Callard. Miller tells Murphy that he wants to kill another gang member called Richard Holloway. Murphy stops the planned arrest because he thinks he can gain Callard's trust and infiltrate the entire criminal organisation to take everyone out.

Murphy tries to get counterfeit Euros for Callard, and asks fellow undercover officer Jill Calder for help. She has infiltrated an organisation that is printing the fake money. Together they try to set up a deal for both their clients and plan to make the big arrest during the handover.