Would you rather be trapped in a creepy old castle with a ghost or a Nazi spy?
Twelve-year-old Katherine Bateson believes in a logical explanation for everything. But even she can’t make sense of the strange goings-on at Rookskill Castle, the drafty old Scottish castle-turned-school where she and her siblings have been sent to escape the London Blitz. What’s making those terrifying sounds at night? Why do the castle’s walls seem to have a mind of their own? And why do people keep mysteriously appearing and disappearing? Kat believes she knows the answer: Lady Eleanor, who rules Rookskill Castle, is harboring a Nazi spy. But when her classmates begin to vanish, one by one, Kat must face the truth about what the castle actually harbors — and what Lady Eleanor is — before it’s too late.