Detective Grace Macallan is unsure of whether she has the strength to continue with her role in serious crime. An undercover officer is missing and a woman washes up, traumatized and barely alive, on the shores of Berwickshire. She has witnessed horror on the dark waters of the North Sea, and her ordeal to survive turns her life into a nightmare. As she untangles the woman’s story of trafficking and abuse, Grace must pit her wits against a brutal gangland boss, knowing he’ll stop at nothing to protect his criminal empire.