Greenmantle is the second of five novels by John Buchan featuring the character of Richard Hannay, first published in 1916.
Hannay is called in to investigate rumours of an uprising in the Muslim world, and undertakes a perilous journey through enemy territory to meet his friend Sandy in Constantinople. Once there, he and his friends must thwart the Germans' plans to use religion to help them win the war, climaxing at the battle of Erzurum.
The book opens in November 1915, with Hannay and his friend Sandy convalescing from wounds received at the Battle of Loos. Sir Walter Bullivant, a senior intelligence officer, summons Hannay to the Foreign Office. Bullivant briefs Hannay on the political situation in the Middle East, suggesting that the Germans and their Turkish allies are plotting to create a Muslim uprising, that will throw the Middle East, India and North Africa into turmoil. Bullivant proposes that Hannay investigate the rumours, following a clue left on a slip of paper with the words "Kasredin", "cancer" and "v.I" written by Bullivant's son, a spy recently killed in the region...
