Crime drama series starring Anna Friel and Nicholas Pinnock. After leaving the force for the sake of her family, detective Marcella Backland (Friel) is devastated when her husband Jason (Pinnock) leaves her. Hurt and angry, Marcella is convinced to return to her former role in the murder squad when an unsolved serial killer case becomes active again. While following fresh leads, Marcella discovers her husband has been having an affair with Grace Gibson (Maeve Dermody), one of the directors of the company she is investigating. Things become complicated when Grace is murdered, with Marcella the last to see her alive. After experiencing memory blackouts caused by a potential personality disorder, a desperate and confused Marcella is left to piece together a series of broken memories and complex leads to solve a case she is becoming increasingly involved in.