Christopher McCandless could have been a contender. At 22, he graduated from Emory University with an A report card, a Harvard Law School option and a rubber-ball bounce in his step that is the stuff of a job recruiter's dreams.

Instead, he became a somebody, catapulted by a Thoreau-inspired obsession and immortalized by a 1998 best-seller. Giving his life savings to charity, cutting up his I.D.s and blowing off his family, Christopher began a knockabout journey into America that ended in a fateful stand-off with nature in the Alaskan wild.

One wonders if budding McCandlesses are going to be inspired or inhibited by "Into the Wild," the absorbing, generous-hearted movie that Sean Penn has made from Jon Krakauer's book. They certainly won't be bored. Penn's narrative surges forward and twists about like the Grand Canyon river his character navigates with devil-may-care abandon. Given the film's airy 140-minute length, that's nothing to be sneezed at.

Emile Hirsch seizes his star-making moment and runs like the wind as Christopher, a resolute maverick with the perceptiveness of a guru and the short-sighted arrogance of youth. He shares with a transient friend the insight that he can appreciate that "some people think that they don't deserve love," and yet he lacks the foresight or compassion to forgive his parents their violence and deceptions. Railing against society in practiced words cribbed from Jack London and "Walden Pond," he can sound like a bit of a bonehead at times. Hirsch, whose ragged prettiness and reserves of intelligence recall River Phoenix, lets it all hang out. He doesn't ask us to love him.

Christopher's dysfunctional home life plants the seeds for his trek of self-liberation, which begins in Atlanta, drifts northwest toward South Dakota and west to the Salton Sea, dips into Mexico and ends in an abandoned bus in Alaska. Like his protagonist's snaking trail, Penn's episodic, non-linear narrative jumps in time and winds back on itself, interweaving Christopher's road trip with flashbacks to his noisy homelife (William Hurt and Marcia Gay Harden are his embattled parents). These latter scenes are taken from the pages of his sister Carine's letters and diaries, conveyed in voiceovers with a fulsome lilt by Jena Malone.

Along the way, Christopher learns how to operate a threshing machine from a vivacious South Dakota farmer (Vince Vaughan), steals the heart of a 16-year-old songbird (Kristen Stewart), ingratiates himself to an elderly leather engraver (a touching Hal Holbrook) and fills a void in the nomadic life of a graying hippie couple. They are played with such ruddy warmth by Catherine Keener and Brian Dierker (a Grand Canyon contractor making a groovy acting debut), we are as delighted as Christopher when chance brings them back into his trajectory a second time.

Penn's direction and writing, like his acting, is emotive to a fault: he can't resist the teary close-up or the throbbing montage of folks whose lives Christopher has touched. But it comes from a good place, a high regard for the profundity and necessity of human connections; a place his hero only fully comprehends when it's too late to make good on the knowledge. "Into the Wild" is a bittersweet odyssey of opportunities lost and paradise found.

INTO THE WILD (R). The Atlanta-to-Alaska odyssey of a bourgeois college graduate with Thoreau dreams, based on the nonfiction account by Jon Krakauer. Sean Penn's sprawling, lovingly crafted film is crowded with the sort of big-hearted, life-toughened characters one would hope to run into while tramping across America. Emile Hirsch makes a vivid impression as the self-styled adventurer. 2:20 (language and some nudity). At AMC Loews Lincoln Square 13 and Landmark Sunshine Cinema in Manhattan.