Conrad Anker is one of the greatest and most notorious professional mountain climbers in history. But at 54, his career in the big mountains is winding down, especially after suffering a heart attack on a climb high in the Himalayas. His friend Alex Wildman is a novice big-wall climber and cardiac nurse with his own history of traumatic illness. Together, they team up to support each other on a climb up Yosemite's El Capitan in Yosemite Valley..