A dismembered leg sent to Strike's office sends both his and Robin's lives into disarray, forcing them to confront spectres from their pasts.

Strike and Robin's partnership reaches breaking point as Robin's wedding approaches, and they disagree about how to ensnare a man who abuses children.

A startling discovery seems to confirm the story of the strangled child, but the team are forced to leave the scene before they can properly investigate. Fearing their witness is in danger, they redouble their efforts to find him.