The Marathon des Sables is a six-day, 250km race across the Sahara Desert: six marathons in six days in temperatures of 50 degrees through some of nature's most stunning landscapes. Why would anyone put themselves through such a physically and mentally destructive challenge? Thousands start the race, hundreds don't finish. We follow four friends who now live across the globe but have come together to do what some describe as 'the toughest footrace on earth'. Show less