In the late '90s Claire Church (Anne-Marie Duff) was an ambitious young detective in Manchester. Finding herself ignored in the office and second place in her relationship with her married boss, she quit the job. She now lives on a remote Scottish island with her family, but when bodies are unearthed on a building site back in Manchester, Claire battles with whether or not to return. She's compelled to find justice for the victims she failed, but knows that going back will come at a price. As fresh bodies turn up and the killer leaves macabre messages directed at Claire, the emotional barriers she's built to protect herself begin to crumble. Can she learn to forgive herself, and finally solve the crime that defeated her?