One minute, Dan Cooper was a real man. Of course, “Dan Cooper” may not have been the name on his birth certificate, but his body was corporeal enough as he stood in a Boeing 727-100 on November 24, 1971. A stairway dangled dangerously from the belly of the near-empty airliner flying over southwestern Washington. No one knows whether he leapt confidently off those open steps from 10,000 feet in the air, or maybe closed his eyes and inched downward into the storm outside. But exit he did, and in that moment birthed something new: one of Washington’s biggest legends. Fifty...