If you don't already know the details (I didn't), the book tells the story of the tragic events that occurred in 1996 as several groups simultaneously attempted to climb Mt Everest.
Krakauer, as a columnist and editor-at-large for Outside magazine (and experienced climber), was asked by the magazine to join a guided expedition on Everest - not to climb the peak, but to remain at base camp and document the increasing commercialization of the mountain. He declined, mostly because he felt it would be too frustrating to be so close to the challenge of the mountain without ascending higher than base camp (altitude of 'only' 17,600 feet). Later he asked Outside if they would consider booking him with one of the more reputable guide services (and cover the $65k fee) to give him a chance to reach the summit (29,028 feet). They surprised him and agreed, and off he went.
Just as with Into The Wild, after reading the first chapter of Into Thin Air you know how the story ends. This became much more than a documentary account of the increasing traffic on the mountain: it was a struggle for survival, and not nearly everyone survives.
Included in the book are several photos taken at or near the summit of Everest. It is clear in the photos how extreme the conditions were, and also how difficult it was to tell who is who due to the amount of gear/clothing each climber was wearing. This is relevant, as the story reveals - "is that a guide, or a fellow client, or a Sherpa?" etc. With wind-chill temps reaching minus-100 degrees, and at an oxygen-depleted altitude over 29000 feet, your life depends on every decision that you make. Throughout, it is revealed that poor decisions were made by guides and clients and Sherpas alike. At the same time all were challenged to be heroic and many responded in ways that cannot be imagined by someone sitting at sea level.
The story is so incredibly told that it's easy to forget that it's true, and that Krakauer was there, living (barely) through the drama. One of my favorite reviews of the book included the following, from Mirabella:
"Though it comes from the genre named for what it isn't (nonfiction), this has the feel of literature: Krakauer is Ishmael, the narrator who lives to tell the story but is forever trapped within it...Krakauer's reporting is steady but ferocious. The clink of ice in a glass, a poem of winter snow, will never sound the same."Indeed.