The SAS is, simply, the most mysterious, feared and secretive elite military unit in the world. Its specially selected and highly trained soldiers have been involved in covert operations, often behind enemy lines, for more than 70 years. During that time they have performed seemingly miraculous feats of military prowess. They have been credited with turning the course not just of individual battles, but whole wars. And while they shun the limelight, every time they are in action, controversy is never far away.... But who are these soldiers? How are they selected and trained? What do they actually do? And what is it that makes them special?