The novel is set during May and June 1914; war was impending in Europe, Richard Hannay the protagonist and narrator, returns to his new home, a flat in London, after living 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. The man appears to know of an anarchist plot to destabilise Europe, beginning with a plan to assassinate the Greek Premier, Constantine Karolides, during his forthcoming visit to London. The man reveals his name to be Franklin P. Scudder, a freelance spy, and remarks that he is dead, which holds Hannay's attention. Scudder explains that he has faked his own death to avert suspicion. Scudder claims to be following a ring of German spies called the Black Stone who are trying to steal British plans for the outbreak of war. Hannay lets Scudder hide in his flat, and sure enough the next day another man is discovered having apparently committed suicide in the same building. A couple of days later Hannay returns home to find Scudder dead with a knife through his heart.
Greenmantle
Finding Stumm plans to send him to Egypt via London, Hannay flees into the snowbound countryside, tracked by the vengeful colonel. He falls ill with malaria and is sheltered during Christmas by a poor woman in a lonely cottage. On his sickbed, he realises that the clue "v.I" on the piece of paper may refer to von Einem, the name he overheard.
Recuperated, he carries on, travelling by barge carrying armaments down the Danube, picking up with Peter Pienaar, who has escaped from a German prison, along the way. They pass through Vienna, Budapest and Belgrade, and as they travel, Hannay connects the phrase "der grĂ¼ne Mantel" with something else he overheard earlier. They reach Rustchuk on 10 January, with a week to go before the rendezvous in Constantinople.
On arrival, Hannay has a run-in with Rasta Bey, an important Young Turk, and intercepts a telegram showing his trail has been detected. They travel by train, fending off an attempt to stop them by the angry Rasta Bey, and reach Constantinople with half a day to spare.