The year: 1917 - and the eve of an appalling disaster, as General Nivelle and his poilus, desperate to expel the invader from their homeland, are about to hurl themselves at the impregnable Hindenberg line. High above the blood-soaked fields of France, fighting with equal desperation, flies a breed of young men who are either quick or soon dead. They are the airmen of the Royal Flying Corps, of the Imperial German Air Force, of the French Air Service - knights of the sky, last heirs of the chivalric tradition, duelling in their fragile flying machines, living with abandon and dying with glory. This is the story of one duel - between a young French man with an ancient name, and who is dedicated personal vengeance; and the German veteran ace Kupper, tormented by love for his Vaterland and a loathing for legalised slaughter.