On 10 May, the Germans launch their invasion of France and the Low Countries, and Armstrong, cut off from the British forces and RAF squadrons fighting in the north, finds himself flying with the French Air Force as the Allies strive in vain to stem the enemy advance.
Armstrong is in the thick of the fighting, taking off day after day in the teeth of hopeless odds, experiencing the agony of seeing his friends fall in flames, their numbers constantly dwindling. Those who survive will become the fighter aces - men with a grim determination to take the war back to Germany one day.