Five months after the events season 1, DS Marcella Backland is called to a house where a body has been found. She is shocked to discover that she knew the victim a 9-year-old boy, Leo Priestley, who disappeared four years ago after agreeing to walk home with her son.

A convicted paedophile; an aging Rockstar and his agent; a self-made millionaire and his wife, the founder of a successful children's charity; and a veteran of Afghanistan struggling to support his sister and her baby are soon all on the investigating team's radar. Even relatives and colleagues fall under suspicion.

Meanwhile Marcella is finding it harder and harder to keep her violent fugues under control and her therapist suggests that the only way she can be rid of them is to revisit their source - the painful loss of her baby by submitting herself to hypnosis.

After leaving the force for the sake of her family, detective Marcella Backland is devastated when her husband Jason 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, 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.