It is 1918. When Paul Peachy, a shy young railway employee and amateur actor from Milwaukee, realises suddenly that his wife no longer loves him, he enlists as a private in the U.S. army and boards ship for the trenches of France. Peachy finds temporary solace in friendship amid the horrors of war, but is soon captured by the enemy in no man's land. His only chance of survival is to impersonate one of the enemy's most famous spies (as the child of immigrants, he is a fluent German speaker). As the urbane and accomplished spy Harry Stroller, Peachy is feted as a hero by the German top brass and gains access to a previously unimagined world of sumptuous living. But his new role also reveals inner reserves of courage and ingenuity he never knew he possessed, as the mounting suspicions of his German hosts force Peachy into ever more outrageous deceptions. In this dangerous world of smoke and mirrors Peachy falls in love with Annie, a beautiful French courtesan who seems to see through his artful disguise...