After graduating in May 1990 with high grades from Emory University, McCandless ceased communicating with his family, gave away his college fund of $24,500 to Oxfam, and began traveling across the Western United States, later abandoning his 1982 Datsun B210 after a flash flood.
He spent time in Carthage, South Dakota, laboring for months in a grain elevator owned by Wayne Westerberg before hitchhiking to Alaska in April 1992.
Krakauer also relates the stories of some other young men who vanished into the wilderness, such as Everett Ruess and Carl McCunn.
McCandless survived for approximately 113 days in the Alaskan wilderness, foraging for edible roots and berries, shooting an assortment of game—including a moose—and keeping a journal.
Although he planned to hike to the coast, the boggy terrain of summer proved too difficult, and he decided instead to live in a derelict camping bus left behind by a road construction company.
Krakauer first speculated that the seeds were actually from Hedysarum mackenzii, or wild sweet pea, instead of the Eskimo potato, which contained a poisonous alkaloid, possibly swainsonine (the toxic chemical in locoweed) or something similar.
In addition to neurological symptoms, such as weakness and loss of coordination, the poison causes starvation by blocking nutrient metabolism in the body.
[8] According to Krakauer, a well-nourished person might consume the seeds and survive because the body can use its stores of glucose and amino acids to rid itself of the poison.
However, when the Eskimo potatoes from the area around the bus were later tested in a laboratory of the University of Alaska Fairbanks by Dr. Thomas Clausen, toxins were not found.
Krakauer later modified his hypothesis, suggesting that mold of the variety Rhizoctonia leguminicola may have caused McCandless's death.
"[18] Despite its critical acclaim, the book's accuracy has been disputed by some of those involved in McCandless' story, and by some commentators such as Alaskan reporter Craig Medred.
Medred covers a large number of items in the book that are questionable, most of which stem from the extremely limited detail in McCandless' journal.