Richard Burton stars as Major John Smith, a British agent during WWII who is in charge a group of six Allied soldiers given the task of rescuing an American general--who is reportedly in possession of the plans for D-Day--from a seemingly impregnable German fortress located high in the Bavarian Alps. Assisting Smith is the sole American in the operative, Lieutenant Morris Schaffer (Clint Eastwood), a fierce soldier skilled with an array of deadly weapons. As the men penetrate the fortress, facing an endless supply of German soldiers, it becomes apparent that some members of the small Allied team may not be who them seem to be. Full of thrilling action set pieces, the screenplay was written by Alistair MacLean, adapted from his own best selling novel.