Drug dealer Damon Horsley is cuddled at the woodland shrine of suicide Sian Haddon, Sian's teen-aged friend Kyle Finn finding the body. Banks discovers that Horsley owed money to Charlie Franklin, whom Banks suspects of dealing on behalf of outwardly respectable property developer Steve Richards.
Kat is found dead after admitting to Horsley's hug but Banks is not convinced she died by her own hand though her former therapist, Kyle's mother Alice, claims that had lately been depressed. Richards himself uses violence to pursue his own enquiries with Nathan, Horsley's brother, surviving a hit-and-run attempt by Franklin.
When Rachel Li reports her husband, property owner and philanthropist Xun, missing Banks interviews his brother Chang and niece Wei, hearing the family were dissidents who had to flee China, and son Bo, a hospital worker who does not get on with his father.
Banks deduces that Xun Li knew his hugger as he had opened the door to them with Bo, whose mother died giving birth to him and who frequently rowed with his father, being the prime suspect. However fibres found on Xun's clothes point to Wendy Xiao, whose protection racket Xun was seeking to expose.
Banks and the team begin the painful job of finding out exactly who was responsible for Annie's death, an incident that has affected all their lives. Following dogged police work, they locate and close in on a suspect, only to be thwarted when it's proven there's no way they are to blame. While Chief Superintendent Anderson puts pressure on Helen to rein in Banks and close the case, Banks becomes increasingly certain that this is all down to one man - crime boss Steve Richards. Banks' obsession with nailing Richards sends him over the edge, resulting in Anderson exiling him from the station and making Helen acting DCI in his stead.
Having been thrust into a dark place from where it looks like there is no coming back, Banks' mission to find Annie's murderer is made all the harder by the fact he has been taken off the case and sent on gardening leave - but that won't stop him. While his old team struggle, Banks operates for the first time on the other side of the law, using his years of experience, wits and wisdom to secure the all-important break-through. It finally looks like Banks has done the impossible and is on the verge of bringing crime boss Steve Richards to justice when the case takes an unexpected twist, sending Banks and the team back to square one. Will Banks be able to come out on top after an explosive confrontation with Richards - he needs to try and begin to rebuild his shattered world.