Blindsight--a sense of perceived vision. When blind educator Sabriye Tenberken, who founded Braille Without Borders, wrote an email letter to the world renowned blind mountaineer Erik Weihenmayer. Weihenmayer would eventually lead six Tibetan teenagers, all of them blind, on a remarkable journey up a 23,000 foot peak on the northside of Mount Everest. We speak to filmmaker Lucy Walker about her recent documentary. You can learn more about the film here.