Greenmantle

Greenmantle is a World War I espionage novel written by John Buchan and first published in 1916.

A soldier-turned-spy is sent on a clandestine mission to uncover a rumor that the Central Powers plan to ignite the East through a messianic uprising cloaked in religious prophecy. A single word—“Greenmantle”—is the key, drawing him from neutral cities to occupied borders and on to Constantinople, where myth and intelligence work collide.

The journey becomes a race across war-torn Europe, a gauntlet of disguises, secret codes, and perilous crossings. As clues converge, the plot reveals a fusion of propaganda, fanaticism, and realpolitik, engineered to shift the balance of the war by stirring mass revolt.

Brisk and atmospheric, the novel expands the template of the modern thriller with high-stakes intrigue on a global stage and a meditation on how belief can be weaponized. It stands as a companion to Buchan’s earlier adventure while pushing deeper into the shadows where empires, rumors, and destinies meet.

"I had just finished breakfast and was filling my pipe when I got Bullivant’s telegram. It was at Furling, the big country house in Hampshire where I had come to convalesce after Loos, and Sandy, who was in the same case, was hunting for the marmalade. I flung him the flimsy with the blue strip pasted down on it, and he whistled."