The Spy Trilogy — John Buchan

The Spy Trilogy includes three spy thrillers. The first one is The Thirty-Nine Steps and followed by Greenmantle, and Mr. Standfast. The Thirty-Nine Steps: Hannay, an expatriated Scot, returns from a long stay in South Africa to his flat in London. One night he is buttonholed by an American who appears to know of an anarchist plot to destabilise Europe, and claims to be in fear for his life. Hannay lets the American hide in his flat, and returns later to find that another man has been found shot dead in the same building, apparently a suicide. Four days later Hannay finds the American stabbed to death. Greenmantle: A classic espionage and adventure novel set during The Great War, featuring the reckless Richard Hannay. Tasked with unraveling a mysterious message, Hannay travels through Germany and the Middle East, searching for the elusive religious leader ''Greenmantle''. Mr. Standfast: Hannay is recalled from the (WWI) western front and given orders to infiltrate a batch of British pacifists looking for a German spymaster operating in England.