The Blurb (from Goodreads):
For Britain's counterintelligence operations, this meant finding the unlikeliest agent imaginable-a history professor named Alfred Vicary, handpicked by Churchill himself to expose a highly dangerous, but unknown, traitor.
The Nazis, however, have also chosen an unlikely agent: Catherine Blake, a beautiful widow of a war hero, a hospital volunteer - and a Nazi spy under direct orders from Hitler to uncover the Allied plans for D-Day...
I love a good spy thriller, particularly when its set during World War II, and Daniel Silva did not disappoint. The unlikely spy of the title is an amiable history professor and he is on the track of a ruthless Nazi spy working undercover in Great Britain in the lead-up to D-Day. This is more a novel of psychological suspense than an action-packed page-turner, but I enjoyed seeing the action from all sides, and found the historical details fascinating.