Sweden, 1942 - Two old friends meet. They are cousins. One is Prince George, Duke of Kent, brother of the King of England.
The other is Prince Philipp von Hesse, a committed Nazi and close friend of Adolf Hitler. Days later, the Prince George is killed in a plane crash in the north of Scotland. The official story is that it was an accident - but not everyone is convinced.
There is even a suggestion that the Duke's plane was sabotaged, but with no evidence, Cambridge spy Tom Wilde is sent north to discover the truth . . .