Happy Valley is a dark, funny, multi-layered thriller revolving around the personal and professional life of Catherine, a dedicated, experienced, hard-working copper. She is also a bereaved mother who looks after her orphaned grandchild.
When Catherine discovers the remains of a gangland murder victim in a drained reservoir, it sparks a chain of events that leads her straight back to Tommy Lee Royce. Her grandson, Ryan, is now sixteen and has ideas of his own about the kind of relationship he wants to have with the man Catherine refuses to acknowledge as his father, leaving Catherine's sister Clare caught in the middle. In another part of the valley, a local pharmacist gets in over his head when a neighbour is arrested.