In the final hours of World War II in Europe, stately Itter Castle in Austria is defended by a handful of U.S. Army and German Wehrmacht troops who join forces in an attempt to hold off a division of battle-hardened Waffen-SS intent on assassinating the French VIP prisoners being held there. Included were two former Prime Ministers, two retired Commanders-in-Chief of the Army, and the sister of Charles de Gaulle. The small contingent of Allies hold their ground until they are down to a precious few rounds of ammunition. They are preparing to sacrifice their lives in medieval-style hand-to-hand combat when one of the most unlikely prisoners, Jean Borotra, formerly the #1 tennis player in the world, volunteers for what seems to be a suicide mission - run through enemy lines in an attempt to seek help.