After a storm reveals the body of Isla Edwards with a knife wound in the Scottish Borders’ Scales Valley, police officer Fiona MacLeish is drawn into the investigation. With only Isla’s diary as a clue and trapped with the locals at a farm due to floodwaters, Fiona navigates tight-knit community secrets to find the killer. Amidst growing tension and with her past haunting her, Fiona races against time to prevent more deaths in the isolated community.