I just finished The Spies of Warsaw. I read it in pretty much one sitting during a flight with multiple stops. In many ways it's like most of Furst's. The hero is struggling against vast odds in the buld-up to World War II. Colonel Mercier is the military attache in the French embassy in Warsaw. He dabbles with espionage on the side. And he has a sad past, being a widower. In his Warsaw job he controls some spies and does some espionage himself.
What interested me the most about the book is how, through the encouragement of a mentor in the the French intelligence service, he finds a way into the the German military high command. This involved dangerous trips to areas under Germna control and eventually even Berlin. Yet because the information he brings back isn't what the French army leaders want to hear, they find a way to disregard it. They are too committed to the Maginot Line. Is it true then, that often people do control their own destinies and fail by refusing to see the truth?
At least Mercier gets a promotion and finds a new wife. We learn at the end that the couple flees France for England when the Germans invade. Mercier works with DeGaulle to eventually liberate France.