John Hannay, after surviving the actions of the Black Stone, the cabal of German spies from The 39 Steps, is now a soldier fighting in France during WW1. He receives a message from Bullivant, Head of the Foreign Office and his old ally from before the war. From there he and others are embroiled in a great german plot to secure the near east.
The adventure takes him from Portugal to Germany and finally to the deepest parts of Turkish Anatolia, as he and his friends attempt to solve the dying mystery left by Bullivant's son, and to work out just who or what is... Greenmantle.

The second of John Buchan's tales of Richard Hannay, Buchan wrote the story during the war, whilst attached to British HQ's Intelligence section. Widely popular at the time, supposedly read by Baden Powell and the Russian Imperial Family.

Narrated by Michael Ward.