When the body of a young male hiker is discovered in Alaska’s Denali National Park, Outside magazine assigns journalist Jon Krakauer to cover the story. The young man turns out to be the runaway son of a well-to-do East Coast family, Christopher (Chris) McCandless, who after graduating from Emory University in May 1990, gave away his savings to charity, abandoned his car, burned all his cash, and hitchhiked across the country “to live off the land” in the Alaskan wilderness.
Five months earlier, on April 28, 1992, Jim Gallien, driving on the outskirts of Fairbanks, Alaska, spots a young hitchhiker and offers him a ride. The young man is Christopher McCandless, but he introduces himself as “Alex” and says that he intends to “live off the land for a few months” in Denali National Park. Gallien, noticing that Chris’s backpack is far too light to be carrying enough supplies for an extended camping trip, tries to dissuade from hiking alone into the woods. But Chris refuses Gallien’s advice, so Gallien insists that the young man take his lunch and boots with him. Chris reluctantly accepts these gifts and walks onto the snowy Stampede Trail. Gallien figures that the boy will reemerge out of the forest when he becomes hungry.
Later that year, in September, a trio of moose hunters, a couple from Anchorage and an ATV driver, happen upon an abandoned bus in Denali National Park, where they discover Chris’ decomposing body. Alaska State troopers recover the corpse, taking it to a crime lab, which determines the cause of death to be starvation.
Two months after the discovery of McCandless’ body, Krakauer interviews grain elevator operator Wayne Westerberg, who recounts the day he picked up Chris, (going by “Alex” at the time), on his way back to Carthage, South Dakota. Chris works so hard on Westerberg’s grain elevator crew that Wayne offers him a job. Yet Wayne is arrested for stealing satellite TV codes, forcing Chris to hit the road in search of work.
Going back to October 1990, McCandless’ yellow Datsun is found abandoned in the Lake Mead National Recreation Area. Through his research, Krakauer figures out that after a flash flood dampened the Datsun’s engine, Chris abandoned the malfunctioning car to conceal his predicament from his parents and the authorities.
Chris then hitchhikes throughout the west. Along the way, he camps with drifters Jan Burres and her boyfriend Bob, flips burgers at McDonald’s in Bullhead City, canoes the Colorado River to Mexico, and befriends eighty-one-year-old Ronald Franz.
On March 14, 1992, Chris returns to Carthage to work for Wayne Westerberg, but leaves at the end of the month, having gathered just enough money and supplies to pursue his dream of living out in the Alaskan wilderness.
Hitchhiking north, Chris arrives in Alaska on April 18, 1992 and crosses the Teklanika River onto the Stampede Trail ten days later. Off the Sushana River, Chris discovers an abandoned city bus, where he makes camp. Throughout the summer, Chris hunts and forages, eventually shooting down a moose. Butchering the moose’s messy carcass to preserve its meat fills Chris with regret, but through reading, journaling and self-reflection, McCandless comes to terms with his kill and decides to return to civilization.
However, the thawing summer floodwaters of the Teklanika River prevent Chris from crossing, so he returns to the bus to regroup.
On July 30, Chris frantically writes in his journal that he is very weak and in grave danger, but also mentions potato seeds. Too weak to hunt or gather, McCandless dies soon thereafter, having spent his last days discovering that the greatest happinesses in life must be shared with others.
Investigating the potato seeds further, Krakauer theorizes that McCandless died of swainsonine poisoning after consuming wild potato seeds laced with a toxic mold.
Having solved the mystery of McCandless’s death, Krakauer accompanies Chris’ parents’, Walt and Billie, to pay their respects at the bus where Chris died. Though comforted by the surrounding landscape’s beauty, Walt and Billie leave still nursing heavy hearts.