The corpse of a high class call-girl, Sonya, is discovered in a trunk at Heathrow Airport. The prime suspect is a highly influential Ukrainian billionaire, Vitali Malikov, and - against diplomatic advice - Mike Walker arrests him, aware that Malikov has friends in high places, for which reason he is keen to bring him down.
Another working girl, Maryna, is put on trial for assaulting Malikov. She claims self-defence but the trial is mishandled and walker is even more adamant then before that he will get the Ukrainian. Roisin, however, believes that his obsession with Malikov is blinding him to the identity of the real killer of Sonya and takes the investigation down a different route.
Surgeon Jonathan Carlisle, a friend of Mike Walker, is murdered and suspicion falls on Gary Webster who blamed Carlisle for the death of his daughter Amber during an operation. However, two other doctors come into the frame - Neelah Shahjani, who confesses that she found the dead man with a needle in his arm,and the helpful Dr. Lawson, who is prepared to show a video to prove that the hospital was not culpable for Amber's death.
Dr. Lawson's assertion that the hospital was not responsible for Amber's death is thrown into doubt with the death of the prime suspect. Mike Walker has to put aside the fact that the deceased Jonathan Carlisle was a friend of his as he uncovers a sordid side to the man's character in his efforts to apprehend the murderer.
Recovering alcoholic Ken Randle seeks revenge on Terry Dyer, just out of jail, whom he believes killed his son Mark twelve years earlier, though Dyer has always protested his innocence, claiming the killer was Nick Fisher, who Mark caught having sex with his sister Sarah,then only thirteen. Then Nick Fisher is killed. His widow identifies Dyer as hanging around Nick's workplace but CCTV proves that he was some miles away at the time of the murder.
Dyer is released and Ken Randle confesses to Fisher's murder and goes on trial. However, Sarah comes to see Walker. She is anxious to tell him what really happened on the night that her brother was killed. As a consequence the charge of murder against Randle seems less likely but the remainder of his family will never be the same again.
Mike Walker is on leave when an old friend, Bill, asks for his help. His sister Margaret disappeared some years earlier and he has recently been contacted by a woman whose daughter, Anna, has also gone missing. The common link is that both were married to a man named Kevin Reid. D.I. Mullins, who was in charge of Margaret's case, is bullish but lets Walker in on his findings. Eventually Margaret's body, minus the legs, is found in a large box.Evidence points to the culprit being Kevin's brother Ronnie, a simple lad with a speech impediment.
Whilst Anna's diary entries initially suggest that Ronnie was stalking her, they are eventually dismissed as forgeries. Ronnie also had an alibi for the time that Margaret went missing and it looks as if he is being framed, possibly by his brother, with whom there is an explosive showdown at a race course.
Self-made man Ray Herper and his bright teenage son Andy are seen to be driving at a chalk pit. The next day the corpse of young Maria Cole is found there and the police trace the tracks to the Harpers. Andy has a friend Darren, who is lower class and has had dealings with the police. The boys admit to being at the quarry but deny all knowledge of Maria. In fact she was a lap dancer at a club to which Harper took Andy but he fled from her. CCTV footage at a garage where Maria went after being threatened by hoodies shows her getting into a car with Andy and Darren and ...
Ray Harper is devastated to find that Andy has hanged himself. Darren admits that he and Andy were a gay couple but dared not tell their families. The case against him collapses and he is released. Mike Walker is having troubles of his own with his teenage son but when Roisin decides to visit Darren at his flat she is in for a shock.