Twenty years after the fall of the Third Reich, West Berlin remains infested with ex-Nazis. Quiller, an undercover Nazi hunter for British intelligence, reluctantly accepts an assignment to uncover a Nazi organization called Phoenix and learn their plans for starting a non-nuclear World War III that would bring the Reich back to power. Two fellow agents have already died trying to accomplish this objective, and Quiller's superiors are quite certain he will be the third.
This is the plot to the 1965 espionage novel, The Quiller Memorandum
(originally published as The Berlin Memorandum). In it, author Elleston Trevor writing as Adam Hall creates a spy hero unlike any others, devoid of the swashbuckle of a James Bond or the bureaucratese of a George Smiley. Having served as a spy behind enemy lines during the war, Quiller is now middle-aged and has grown tired of his job, but realizes it is the only thing that makes him feel alive. He also has a personal reason for accepting what appears to be suicide mission: one of the Phoenix crowd is said to be a long missing Nazi whom Quiller had personally witnessed execute dozens of Jews.
The Quiller Memorandum is more a psychological thriller than an action thriller. The first person narrative spends more time discussing the psychology of espionage -- such as how to out think a pursuer, or the mental attributes needed to withstand interrogation and torture -- than it does describing shoot outs or fist fights. An entire section of the book describes the mental acrobatics needed to break a cipher code.
That may not sound exciting if you enjoy your spy novels full of bomb blasts and car chases, but Quiller is an intensely gripping read if you like more realistic espionage stories. And if you like historical settings, Quiller has it -- though at the time of its writing, the settings were all contemporary.