In 1808, trapper John Colter ran and climbed 150 miles through what is now Yellowstone National Park to escape a hundred pursuing Blackfoot warriors. In 1823, hunter Hugh Glass, left for dead after a bear attack, crawled 100 miles from the Grand Valley to the Missouri River. Tortured in mind and body, these two men came to embody the spirit of survival. Finally we have their story—an epic saga, stirring as the wilderness itself, bold as the people who came west to tame it.