Thursday, Doug is joined by National Geographic Explorer-in-Residence Wade Davis for a look at British attempts to conquer Mount Everest in the early 1920s. George Mallory is the most recognizable name from the expeditions, but Davis wanted to go beyond the icon of mountaineering to explore the spirit that drew the group to such heights. Davis has called the expeditions "a mission of regeneration and redemption for a nation bled white by war." His book is called "Into the Silence."