Every year hundreds of thrill seekers from around the world apply to run a 160-mile course through Tennessee’s treacherous Frozen Head State Park, though fewer than 40 people are granted the privilege. This enlightening documentary (2015) chronicles the 2012 marathon from the perspective of its eccentric founders, affectionately referred to as “sadists,” and its participants, who are mostly well-educated achievers adrenalized by the possibility of failure. Codirectors Timothy Kane and Annika Iltis provide helpful graphics between scenes—in terms of elevation, the course is equivalent to climbing and descending Mount Everest twice—and provide plenty of context as to why one would choose to push one’s body and mind to their breaking points. “Most people would be better off with more pain in their lives,” remarks one participant. Cut to the remaining runners, their ashen faces breaking into grins at the finish line.