Each year, more than 1,000 mountain climbers venture to Denali National Park in Alaska and attempt to reach Mt. McKinley's summit, the highest point in North America. Nearly half of those adventurers fail, and several die trying even some of the most physically fit and well-equipped climbers succumb to a strange and confounding sickness brought on by severe cold and high altitude. In an exploration of extreme medical science, NOVA ascends to the top of Denali to try to solve the mystery of high altitude deaths on one of the most dangerous mountains on earth. Deadly Ascent chronicles daring mountain rescues, emergency medical evacuations, and cutting-edge science experiments as a team of researchers, doctors, and mountaineering experts employing the latest NASA technology investigate the lethal diseases attacking climbers all over the world. The highest mountains on earth have always lured adventurers to their peaks, where climbers push the limits of survival. Thanks to the efforts of researchers and rescuers, scientists are coming closer to deciphering the deaths on Denali and determining the body's point of no return in these extreme cold and high altitude conditions.