The Sleeper — J. Robert Janes

A schoolteacher enters a war of shadows to save his daughter from the 3rd Reich

David Ashby spent the last war killing Germans, and the years after falling in love with one. By the time Hitler comes to power, David has a half-German daughter, Karen, whom he loves more than life itself. So when Europe begins to slide toward war, and it becomes unsafe for an American to stay in the Fatherland, David does the only thing he can: He flees -- and takes his daughter with him.

David takes refuge in England, becoming a teaching master at a quiet country boarding school, and places Karen with friends on the Cornwall coast. But Hitler will not part with a daughter of the 3rd Reich so easily. German intelligence sends a sleeper, a dormant agent awakened, to finish off David and recover his child, drawing the mild-mannered schoolteacher -- and the British intelligence services -- into the thick of a secret war. Caught between 2 armies of spies, David will do whatever it takes to preserve Karen's freedom.