"In wartime, truth is so precious that she should always be attended by a bodyguard of lies." ~ Winston Churchill
Before he became famous for his contemporary spy thrillers, Daniel Silva wrote The Unlikely Spy. The story of college professor Alfred Vicary, who in the midst of WWII is caught up in the British government's desperate efforts to keep the plans for the D-Day invasion secret. Vicary is a most unlikely spy-catcher and his adversary, a secret Nazi agent, is indeed a most unlikely spy. Even though you already know how the D-Day invasion turned out, this spy thriller will keep you on the edge of your chair.
If you want more WWII spy novels try:
The Honor of Spies by W E B Griffin
Black Cross by Greg Iles
The Key to Rebecca by Ken Follett
The Polish Officer by Alan Furst