In this episode, we explore two of the most haunting missing persons cases in the Great Smoky Mountains National Park.First, the mysterious disappearance of 16-year-old Trenny Gibson, who vanished without a trace during a school hiking trip in 1976.Then, we rewind to 1969 and examine the baffling case of 6-year-old Dennis Martin, whose family Father’s Day camping trip became one of the National Park's most extensive and controversial search-and-rescue efforts.