Greenmantle

Hannay is taken out of a hospital bed in 1915 and sent east on almost nothing: a prophet is being raised in the German interest to set the Muslim world alight, and three words on a dead man's paper are all that anyone has. Buchan wrote it while running Britain's wartime propaganda and knew exactly how such a rumor would be manufactured. The journey runs from Lisbon to Erzerum, and the villain is among the best he ever made.