Sarah Lancashire will make her comeback in the highly acclaimed BBC thriller written by Sally Wainwright. Serious police officer Catherine Cawood returned to Calder Valley in West Yorkshire to lead her dedicated police team. While on duty, she discovered a terrifying corpse. The injuries of the victims are strikingly similar to a series of other murders that took place in the previous months, which indicates that a serial killer is at large. But when Catherine met the victim, the case became even more shocking - it could have a serious impact on herself and her family.