It is late May in Alaska, the height of the climbing season in the world's most treacherous mountain range. Three Englishmen are clawing their way up the sheer West Rib of Denali, the highest mountain in North America. During a break in the weather, they attempt a mad dash for the summit 4,000 feet above them. Twelve miles away, clinging to a vertical wall of ice, two experienced American climbers also see the break in the clouds as their chance to reach the summit of Thunder Mountain, the third highest in the Alaska Range. But, as every mountain guide preaches, good weather is the most dangerous: it always goes bad when you least expect it. And what neither climbing party knows is that two weather fronts are about to collide above their heads to create one of the most hellacious storms Alaska has ever seen. Within twelve hours the three Englishmen are trapped at 19,000 feet on Denali in whiteout conditions, hypoxic and dehydrated, their radio frozen, while one of the Americans has narrowly escaped death in a fall and is now pinned to a narrow ledge, depending on his wounded partner to reach the help that will save his life. With