The Disappearance of Stacy Ann Arras is a haunting unsolved case from 1981 involving a 14-year-old girl who vanished during a guided horseback hiking trip in Yosemite National Park. She was last seen walking slightly ahead of the group near Sunrise High Sierra Camp, but when the group regrouped, Stacy was gone. Despite immediate alerts and one of the largest search efforts in park history, no trace of her was ever found. The vast wilderness, lack of evidence, and unanswered questions have made her disappearance one of Yosemite’s most disturbing and enduring mysteries.