It is 1944 and the British Army has the 'strangest, most individualistic and most secret unit to wear uniform. . .X-Troop.' This special unit of anti-Nazi German, Hungarian and Austrian volunteers are given new British identities. One of them, Stephen Rigby, is a German Jew by birth. He is chosen for a secret and dangerous assignment: to present himself to the Germans in France as a French spy. He has to convince them that the planned Allied landing is to be at the Pas de Calais, diverting the Germans from the location of the real invasion. Thousands of lives depend on his success.