Katherine Bateson along with her brother, Robbie, and sister, Ame, are sent to school at Rookskill Castle in Scotland from London, England.  Their parents want them out of the city, safe away from the London Blitz. But there’s something very creepy about Lady Eleanor and the Rookskill Castle boarding school. Who are the mysterious children Kat notices around the grounds but not in her classes?  Could one of her teachers be a Nazi spy? When her classmates start to disappear, Kat is determined to discover the secrets of Rookskill Castle.