In the summer of 1967, twelve men set out to climb Denali - then officially Mount McKinley - the highest mountain in North America. Nine of them had been recruited by a 24-year-old graduate student named Joe Wilcox, and most had never met before they arrived in Alaska. The other three were a Colorado team who had lost their fourth man in a car accident weeks earlier, and who were forced to merge with Wilcox's group days before the climb because park rules required a minimum of four. Twelve strangers, one leader, and a mountain that none of them had any real experience of.

Denali in 1967 was a different proposition to Denali today. There was no rescue service. Weather forecasts came from a radio DJ reading out the temperature in Anchorage. Radios were so poor that a message from the mountain had to be relayed through Fairbanks and back again ...