故事描述女警官Catherine（Sarah Lancashire）带领一个调查组来到约克郡一处偏远的山谷调查一起绑架案，但很快发现案情线索复杂。在一连串多米诺骨牌式的事件发生后，这起案件引出了多起更加严重的犯罪。

Sarah Lancashire returns in the acclaimed BBC thriller written by Sally Wainwright. No-nonsense police sergeant Catherine Cawood is back heading up her team of dedicated police officers in the Calder Valley in West Yorkshire. While on duty, she makes a gruesome discovery – a body. The victim’s injuries bear a striking similarity to a string of other murders over the previous few months, suggesting a serial killer is on the loose. But the case becomes even more shocking when it emerges that Catherine knows the victim – something that could have serious repercussions for both herself and her family.