As the clouds of war gather over an unprepared Europe, 1939 sees American journalists Josie Marlow and Mac McGrath narrowly escape the fall of Warsaw and find themselves caught up in the so-called Twilight War - when Hitler prepared to march, and the Allies did nothing to stop him. Polish mathematics genius Richard Lewinski heads a desperate attempt to crack the secret Nazi code; brothers Andre and Paul Chardon organise a heroic defence of the French Cavalry School at Lys; German Captain Horst von Bockman is torn between love of his country and the insanity of war; and David Meyer, an American pilot shot down during an air battle, battles to escape the German onslaught in order to return to lovely Englishwoman Annie Galway.