When former detective Robert and his school teacher wife Katy decide to make major changes to their lifestyle, they impulsively purchase a guest house in the Lake District where they plan to create a haven for holidaymakers. When Mark, a former colleague and friend, approaches the couple asking for their help in providing temporary housing for people needing protection from criminals, their idyllic guest house quickly becomes a safe house.

A police detective finds herself at the centre of the most dangerous case of her life when she is seconded on to the investigation into the murder of a drugs trafficker. What nobody around her knows is that she is the missing witness that the police and the killer are searching for.