When the bombs fall on London, the elderly Duke de Richleau is forced to consider a problem of the utmost urgency. What methods are the Germans using to discover – with sinister effect – the secret routes of the Atlantic convoys? His answer is bizarre and fantastic. Could it really be that the enemy are in touch with supernatural powers? Can these powers only be overcome by those who have the knowledge and courage to join battle with them on the Astral Plane? The Duke and his supporters face the terrifying challenge from the Powers of Darkness.