Happy Valley tells the story of Police Sergeant Catherine Cawood in rural Yorkshire. She is known for her no-nonsense approach and effectiveness in her job.
However, Catherine's stoic exterior hides a troubled past. Her teenage daughter's suicide eight years ago led to her raising her grandson, after her husband divorced her and her son became estranged.
Adding to her struggles, Catherine's sister is a recovering drug addict and alcoholic who lives with her. To make matters worse, the man who raped her daughter and fathered her grandson, Tommy Lee Royce, is about to be released from prison and may return to the area.