Outrun the Sun is the extraordinary story of arguably the ultimate trail challenge. On Saturday June 21st 2014 - the longest day of the year - two teams of trail runners attempted to circumnavigate Mont Blanc between sunrise and sunset. This film documents this amazing relay event, as the runners faced the prospect of covering 152 kilometres of mountainous terrain in a little over 15 hours. During the course of the event they'd climb 8500 metres through France, Italy and Switzerland, in temperatures ranging from 27 degrees centigrade, down to the chill you'd expect with snow at high altitude.