An unconscious man is found in a boat which drifts to the landing of an isolated African outpost where Baron von Ragenstein, an enemy agent, recognizes the man as his exact double, Sir Edward Dominey, with whom von Ragenstein went to school. He plots to kill Dominey and pose as the dead man.He learns about Dominey's broken marriage to Muriel and his relation to Sir Ronald, head of home defense. Back at the Dominey estate,Muriel is delighted with the change in Dominey, and Sir Ronald gives the spy a confidential position.The situation is complicated by Bardinet, Muriel's admirer who, like von Regenstein, is under orders from Seamon, chief of the enemy agents. Another difficulty is Baroness Stephanie, a spy who loves von Regenstein. The jealous Bardinet tells Muriel that Dominey is an impostor and she tells Sir Ronald.