Duel for the Northland

If you had seen a certain tall, impeccably-dressed man in Copenhagen in 1934, you might have taken him for a professor. Plenty of Danes did. He called himself Dr. Erich Ring and said he was a journalist. But his real name was Horst von Pflugk-Hartung, Germany's master spy in northern Europe. After he murdered German communists Karl Liebknecht and Rosa Luxemburg, vengeance on him was sworn by Communist saboteur Ernst Wollweber. Kurt Singer provides the sinister story of cat-and-mouse espionage between German Nazis and Russian-backed Communists on the chessboard of northern Europe. The Scandinavian countries were riddled with spies long before Germany put its war machine into action, and Singer dramatically details such men and women, both heroes and traitors. Duel for the Northland was published in 1943.