The book is a fictional story that takes place during WWII. It centers around two Nazi spies and saboteurs. They put ashore in America by a German U-Boat. Their mission is to make their way to Detroit, a major hub in President Roosevelt's arsenal of democracy. They go to work for the Packard Motor Company. Packard has a $130,000,000 dollar contract to produce the famed Rolls-Royce Merlin engine. These engines will power the P-51 Mustang, arguably the best fighter aircraft of its time. The P-51 will mean that Allied bombers will have fighter escorts to and from targets deep into Germany. Thereby, shortening the war in Europe.The spies are put up in a house in a quiet residential area of Detroit. They begin to make plans on how they can destroy the production facilities of the Rolls-Royce Merlin engines. Things are going as planned until one of the spies falls deeply in love with the girl next door.