An ex-policewoman turned sex therapist finds danger around every corner after investigating a murder involving auto-erotic asphyxiation in this television mini-series from writer Kay Mellor. There are few things that come as a shock to successful sex therapist Linda (Suranne Jones). When Linda's former lover Angie (Eva Pope) contacts her seeking advice about a rather sordid murder case, however, the woman who has heard it all is suddenly thrust into the dark world of fetishes and sadomasochism. At first Linda isn't quite sure what to make of the case, but when the body of a current client is discovered, she begins to suspect that her own life may be in great danger.