On August 5, 2008, uber ultra-runner Karl Meltzer set off on the biggest race of his life. His challenge: to run the entire length of the 2,174-mile Appalachian Trail in less than 47 days. Definitely daunting. Absolutely grueling. Probably insane. But when he does it, he’ll rule the AT as the guy who conquered it, all of it, the fastest on two feet. This is going to be Man vs. Nature, Man vs. Self, Man vs. Clock – and it’s going to be good.