In 1991, in a field near the Nepalese hamlet of Gokyo, four men climbed into two fragile wicker baskets and poured flame into their hot air balloons. They were to become the first balloonists to fly over Mount Everest. 　　For Leo Dickinson and Chris Dewhirst, the cameraman and pilot in one of the balloons, the flight was to settle old scores after three previous attempts and sever...