This film tells the true story of how a bunch of writers, artists, set designers and back room technicians pooled their talents in order to outwit the German High Command and fool Hitler. Espionage, counter espionage, decoy airfields, inflatable tanks, guns and soldiers are all deployed in the run up to D Day to create a massive diversion and the strongest possible indication that the landings will be in Calais rather than Normandy. A whole invisible army is conjured up: FUSAG the First US Army Group. General Patton is placed in charge of this army, such is its importance he is detained in Britain for several weeks after the Normandy landing in order to (successfully) convince Hitler that a second and larger set of landings will be staged in Calais. A true story.