PBS's "Nova" chronicles a scientific study of high-altitude physiology, gauging a group of Himalayan climbers' physical and mental changes as they set out to conquer Mount Everest -- the very pinnacle of Earth. Jodie Foster narrates as the "Nova" camera crew captures Everest's simple but stunning splendor. The drama reaches a gripping climax during the descent, when the fate of a desperately ill climber hangs in the balance.