"I have a bomb here and I would like you to sit by me." ? That was the note handed to a stewardess by a mild-mannered passenger on a Northwest Orient flight in 1971. It was the start of one of the most astonishing whodunits in the history of American true crime: how one man extorted $200,000 from an airline, then parachuted into the wilds of the Pacific Northwest and into oblivion. D. B. Cooper's case has become the stuff of legend and obsessed and...