It's Christmas 1943 and Lady Anne Coke has returned to Holkham Hall from Scotland. But her home is now an army base, with large sections out of bounds. And 11-year-old Anne is in the care of a new governess, whom she hates and believes to be hiding something. At least her beloved grandfather is there with her, to share stories and keep her entertained.

But even though she's been told to stay away from certain parts of the house, Anne knows secrets about the hall that others do not; the passageways and the cellars that allow her to move around unnoticed, watching. And when mysterious events lead to a murder and disappearance, Anne is determined to uncover the truth.