On June 30, 1970, a small Piper single-engine airplane with only a pilot on board disappeared while en route from Boston to Newfoundland in Canada. For three months, no one knew what happened to the plane or the pilot, retired Air Force Capt. Robert McGaunn. But that fall, a local pilot spotted the wreckage of the plane near the top of a mountain in Acadia National Park, and McGaunn’s body was recovered.