One slip, one false move, one missed toehold, and you're dead. Alex Honnold, the #1 free solo climber in the world, chose the route known as Freerider on Yosemite's El Capitan, a series of pitches so hard that it's newsworthy when someone free climbs it with a rope. No one had ever 'free soloed' it before; only a few people have ever even contemplated it. That four-hour climb on June 3, 2017, was, simply, one of the boldest feats in human history. At the same time, it was almost unbearable to watch--as Mark Synnott did.