At three miles above sea level, the base of Mount Everest is already higher than any mountain in the Rockies. The expedition team makes seven overnight stops to get to Base Camp (BC) on the mountain's northern face and will take a full month to acclimatize their bodies before they attempt the summit. The air is thin and the climbers feel physically weak, but the camaraderie is strong. As the team moves to Advanced Base Camp (ABC) at 21,000 feet to begin acclimatization climbs, they are shocked to discover how badly their minds and bodies cope. The expedition members begin climbs up to a ridge at 23,000 feet called the North Col, scaling 1,000-foot ice cliffs along the way.

At ABC, more than 600 climbers prepare for summit attempts. All the climbers on Russell Brice's expedition must prove they're strong enough to climb from ABC to the North Col in less than five hours or he will not allow them to continue.

Russell spots a period of light winds in two weeks' time that looks ideal for an early summit attempt. To make this window, however, he'll have to push both his Sherpas and climbers extra hard to be ready two weeks early.

Team One is the first to head into the death zone, where the extreme altitude shuts down digestion and the body starts to consume its own muscle tissue for energy.

After only a few hours at the top camp, Team One leaves in the darkness at 1 a.m. for the summit. Almost immediately, they are caught in a frustrating human traffic jam that stops them in their tracks. If they can't pass some of the slow climbers on the ropes ahead of them, they could run out of time…and oxygen.

Members of Team One cope with the aftermath of their summit attempts. Many climbers are in danger from frostbite in the minus 40 degree F temperatures.

Russell instructs Team Two, now at the top camp and ready to begin their summit attempt, to leave two hours early to try to beat the traffic. Although this might help, it also means an extra two hours in the elements before the sun rises on a very cold day. While some climbers make a strong start, others immediately struggle.

As everyone descends, the entire team suffers from the extreme cold. Frostbite affects more climbers on Russell's expedition than ever before.

For each one who made the trek, whether or not they made the summit, the most important trip will be the one home. The climbers reflect on this year's expedition and whether or not they'll return to the mountain.