One summer, a 24-year-old runner parker her car on a remote Wyoming road, left behind a to-do list with one uncrossed item "run" and was never seen again. Across the country, another woman was walking with friends on a well-traveled trail in the Great Smoky Mountains, went off ahead of her friends, and vanished without a trace. Today, we're diving into two backwoods disappearances, where the search parties found almost nothing, and the questions still go unanswered.