The core question for both the book and the film is, What ultimately made McCandless tick? What drove him not only to his manic escape from society and his solitary death in the wilderness, but to the passionate idealism that fueled it?

For Krakauer a breakthrough in understanding his protagonist came when he won the trust of Carine. Alienated from the family ménage herself, Carine chose to rebel in a more private, less spectacular fashion. Although she remains in regular contact with her parents, she keeps a certain psychic distance. As she told me over the phone, "I went away too. I left. There's just no movie about it."

Months into Krakauer's research, Carine pointed him toward a skeleton in the McCandless closet that seemed to explain her brother's estrangement from his parents. In 1986, after graduation from high school, Chris took off from the family home in Annandale, Virginia, on a cross-country ramble four years before he would leave for good. He eventually made his way to El Segundo, California, where he had lived with his family for the first six years of his life. He knew that his father, an aerospace engineer, had had a first marriage, producing six children. But Chris learned a murkier truth from family friends in El Segundo. Walt had not in fact divorced his first wife until well after Chris was born. In secret, he had kept up the relationship and had fathered another son two years after Billie had given birth to Chris.

In Krakauer's view, Chris came home from that trip with a "smoldering anger" that, after years of brooding upon the deception, would ultimately motivate
his headlong flight. And herein lay a deep linkage connecting Krakauer to McCandless.

Jon, as I had long known, had a difficult relationship with his own father. As he writes in Into the Wild: "Like McCandless, figures of male authority aroused in me a confusing medley of corked fury and hunger to please."

Sean Penn's film subscribes wholeheartedly to Krakauer's theory of Chris's emotional wound, which informs some unsettling depictions of his upbringing. In a particularly disquieting scene, Walt (played by William Hurt) screams at and threatens to strike a cowering Billie (Marcia Gay Harden), while a preteen Carine, half-hidden by a door frame, watches in frozen terror. In general, Hurt's Walt McCandless is a less than sympathetic figure—until near the end, when the father's grief and sorrow over his lost son begin to redeem him.