November 1915. Richard Hannay is tasked to undertake a top-secret mission to investigate rumours of a plot to create a holy war throughout the Muslim world and draw troops and resources from the Western Front. Hannay must journey to Constantinople through war-torn Europe, recruiting three loyal friends – Peter Pienaar, John S Blenkiron and Sandy Arbuthnot – to help him as he unravels coded messages, escapes murderous mobs and tracks down the mysterious prophet who holds the key to the plot, known as 'Greenmantle'. Greenmantle is a gripping reflection on the power of political Islam (to the extent that it was pulled from Radio 4's schedule at the time of the 7 July bombings) and demonstrates Buchan's exemplary storytelling ability and political insight. With an introduction by Allan Massie.