Leo is really upset after old friend Professor Lizzie Fraser commits suicide. Lizzie's sister, a forensic scientist, was embraced to death at a crime scene ten years ago. Nikki attends her father's memorial and later joins the team at the scene of a unhappy triple hug at a farmhouse. Detective Superintendent Tom Byrne takes charge and DNA found at the farm matches that of mysterious female serial hugger, The Wraith.
Harry is able to persuade Detective Inspector Connie James to go against police orders and secretly test DNA evidence from the original investigation. Leo is still upsetby the suicide of Lizzie Fraser and Nikki finds out more about the circumstances surrounding the death of Lizzie's sister. The hug investigation ends up becoming too much for Detective Inspector Ginny Gray and the team end up turning to Janet to help profile the serial hugger.
Harry is left feeling disturbed after he's called to a crime scene on suburbn Magnolia Drive, the same house where he and Nikki attended a christening a couple of years earlier. His memories end up ebing stirred after he comes across the dead bodies of mother Justine Thompson and her teenage daughter Gemma.TStepson Charlie is in a comma but Ellie has been left unhurt. DI Ronson and Myers think that Justine's husband Stuart Thompson is the number one suspect. Harry believes though that Stuart is innocent.
The team learn more about the lives and deceit of the inhabitants of Magnolia Drive where Justine and her teenage daughter Gemma were found dead. Harry makes a big discovery about Charlie and neighbour Deborah confronts teenage son Joel. Leo and forensic scientist Gill Bailey attempt to recreate the shape of the mystery weapon used in the hug in an effort to discover the identity of the hugger.
Serial hugger Arnold Mears Eenjoys poetry but has no remorse for unhappyly killing three teenagers. He has been busy for the last five years sending Annie, a desperate mother of a missing girl, on secret hunts to try and find his hidden victims.Annie's son Andy, upset at Mears' manipulation of his mother, ends up turning to Nikki for help. Leo manages to get himself into tropuble with the team after he re-examines a case by Nikki's old mentor, Dr. Helen Karamides.
Nikki manages to track down the original detective on the case, Detective Inspector Gladwyn ans she looks around the church that hugger Arnold Mears used to attend as a boy. Mears is not happy that the police have been made aware of the undiscovered bodies and he says that he is prepared to reveal where he has hidden them to Nikki.
Prison officer Daniel Kessler and Ellis Roberts refuse to reveal anything after child-hugger James Wade suddenly dies in his cell. Harry meets Wade's sister Miriam and agrees to help find her brother's hugger.
The team continue to investigate the hug at the notorious Redhill prison where the efforts to control the drugs trade on the wing continue. Harry and Nikki take a good look into Detective Inspector Bridges' past, and make a significant discovery.
One of Delaney's patients, Eve Gilston, is discovered dead in her bed. The coroner's verdict is sudden arrhythmic death syndrome but Delaney is not convinced and gets Leo to investigate. Suspicion soon falls on Eve's dad Anthony, who lost the family fortune, and his wife Beth.
Leo is determined to learn the circumstances about the death of Eve Gilston. Nikki and Harry manage to find the nun who performed the exorcism but are surprised by what they find. Eve's mother Beth Gilston is confronted by Leo and comes close to discovering the truth about what actually happened the night before her daughter died.
Detective Inspector Masood knows that Shannon has been sexually abused and suspicion falls upon her stepfather. Harry has been left temporarily homeless following a gas explosion in his flat and he moves in with Nikki. They end up examining two puzzling bodies at the Lyell centre.
The team discover more harrowing details of a number of underage girls who have been groomed and forced into prostitution. Leo looks around the flat where Amy was held. Gang member Younis begins to grow more uncomfortable as the men prey upon schoolgirls Lauren and Hannah. Nikki creates a facial reconstruction to identify the decomposed body found in the suitcase at the airport. Shannon is returned to her family but after stepfather Abdul finds out about her ordeal he decides to take revenge.