In the closing hours of the defense of Khe Sanh Combat Base, the longest and bloodiest battle of the Vietnam War, Tom Mahoney inexplicably walked away from his platoon, unarmed, and was shot to death by enemy soldiers hiding nearby. His fellow Marines made several desperate attempts to recover their well-liked comrade, but were finally forced to leave him behind-though never forgotten. In The Long Goodbye, author Michael Archer (a...