Yorkshire, 1983. Lorraine Quick's life was looking up with a promotion that took her away from the grim Memorial Hospital and all its bad associations. But now Lorraine has her work cut out for her building a PR-friendly team out of the ragtag staff of the infamous Windwell Asylum as it transitions into a modern, top-security unit housing some of the most dangerous criminals in the country. And then Lorraine discovers a brutal murder has taken place on site despite the fifteen-foot-high perimeter wall and heavy-duty locks.

Between the asylum's lingering reputation for violence, the haunting underground tunnels of the old institution and the arrival of almost-old flame DS Diaz to investigate the murder, events are coming to a head for Lorraine at the old asylum.