The Best Of All Our Spies by Alex Gerlis is absolutely unputdownable. Thoroughly-researched, you can see the bits based on true events if you are a WW2 history geek like me, but it's a very human story showing the devastating consequences of war. If you are interested in the role of women in espionage, and in particular the French resistance, this is the book for you. I hope somebody options it for a movie- it would be fantastic.