Captain Robert Britain, member of the Royal Air Force, is shot down during a dogfight over France. He hides in a castle belonging to Doctor LaFarge, leader of a resistance group. However, Nazis followed Britain to the castle and finding the resistance leader shoot him. Britain finds an armor in the castle which once belonged to a legendary warrior who fought beside Charlemagne called the Iron Ace. Britain puts on the armor for protection and fights against the Nazis. Lafarge then tells him, with his dying breath, where to find a plane that can become armored by command. He remains in the armor and takes to the skies, to battle against more Nazis as the Iron Ace.