The Thirty-Nine Steps. John Buchan

Set in 1914, during World War I, «The Thirty-Nine Steps» is a novel by Scottish novelist, historian, biographer John Buchan (1875 – 1940): Richard Hannay, the protagonist and narrator and an expatriate Scot, returns to his new home, a flat in London, after a long stay in Rhodesia to begin a new life. One night he is buttonholed by a stranger, a well-travelled American, who claims to be in fear for his life.