Near the end of World War II, American Major Falconer (Lancaster, Academy Award winner Best Actor, Elmer Gantry, 1960) leads his weary eight-man squadron to a perfectly preserved medieval castle in the Ardennes Forest. Castle Keep's owner, the ageing Count of Maldorais (Jean-Pierre Aumont), shelters the servicemen in the hope that they will defend his fortress and his priceless collection of art masterpieces from the advancing German troops. But the servicemen have plans of their own. As the German soldiers push forward, a deadly game of possession ensues, leading to a spectacular battle for the castle.