Into the Wild (15)

Sean Penn's version of a young wanderer's complex story turns it into a search for a missing spiritual and political ideal – but you could swat the drifter's halo

Among Hollywood talent, Sean Penn has rather a reputation as a secular saint. It's possibly because, as an actor, he hasn't cracked an on-screen smile in living memory, but in large part too it's because when he directs, he does it with an admirable seriousness. His 2001 film The Pledge – a bleak, poignant adaptation of Friedrich Dürrenmatt's existential detective story – was the best use anyone has made of Jack Nicholson in a film for the past 20 years, and The Crossing Guard (1995) came close. But Penn overreaches himself with Into the Wild, in which his passion and his reverence for the American rebel tradition vault awkwardly into the empyrean realms of piety.

The film undeniably has a striking tale to tell. Based on the book by Jon Krakauer, it's the true story of Christopher McCandless (Emile Hirsch), a young graduate who in the early 1990s walked away from a promising future and set out on the American highway to Way Out Yonder. His dream was a great Alaskan adventure: two years on, he was found starved to death in an abandoned bus that he'd made his home, out in the northern expanses.

McCandless's remarkable destiny is bound to grab our attention and your sympathy – though he forfeits much of the latter by adopting the nom de route Alexander Supertramp. Penn's screenplay finds an intriguing if not always compelling way to delve into the McCandless mystery: a jigsaw structure in chapters that intersperses episodes from his travels with moments from his final weeks in Alaska, as well as flashbacks to life with his stolidly unhappy parents (William Hurt, Marcia Gay Harden) and his sister Carine (Jena Malone).

Carine's intermittent voice-over strives to unlock her brother's psyche. But overall, Penn is less interested in interiority than in grand exteriors, in hymning the glories of a continent. There are numerous self-consciously majestic shots of McCandless, arms outstretched on mountaintops and gorges, the camera swooping euphorically overhead. There are also breathtaking – but inescapably bogus – images such as McCandless walking on a massive fallen trunk in a forest, the sense of scale calculatedly highlighted by a caterpillar wriggling across the foreground.

But beyond such Discovery Channel stuff, Penn attempts a portrait of America: the spiritual and political lost ideal represented by writers such as McCandless's beloved Thoreau and Jack London, and the actual, degraded nation in which a canoe trip down raging rapids involves a $2,000 fee. There are fascinating, quasi-documentary glimpses of a marginal, dissident hippie-legacy America rarely seen in film today, outsider communities such as California's Slab City encampment. But the film doesn't peddle naive illusions about the joys of the road. McCandless, homeless by choice, briefly spends time among the long-term abandoned on the streets of Los Angeles. In the time-honoured boxcar tradition, he is viciously booted off a freight train, in a brutal scene all the more startling to us because it clearly comes as an eye-opener to McCandless too.

McCandless meets some interesting people on his travels, although they seem more interested in him than he is in them. Among them, an ebullient, no-shit farmer (Vince Vaughan), two veteran hippies (Catherine Keener, Brian Dierker) and a teenage folk singer (Kristen Stewart), with whom Christopher politely declines to sleep, preferring instead to duet with her at the microphone (at which point you feel like taking a fly-swatter to his halo). He comes closest to intimacy with Ron (Hal Holbrook, excellent), a grizzled leather engraver and the least stereotypical figure Christopher meets, who's willing to learn the odd life lesson from the younger man. McCandless seems to impart illumination to all he meets, yet it's a one-way transaction: he tells Ron, "You're wrong if you think the joy of life comes principally from human relationships." Such self-containment becomes hard to like.

Another film with its head less in the clouds might have dug further beneath McCandless's contradictions. Glimpses of family strife don't reveal a great deal. But one remarkable sequence – McCandless freezes as a bear lumbers past him – reminds you of a similar doomed outsider, the naturalist Timothy Treadwell who was the subject of Werner Herzog's documentary Grizzly Man, and you wish that Penn had been able to summon some of the investigative detachment that made that very different film so fascinating.

With its free-associative structure and use of Eddie Vedder's clunkingly earnest folk songs, Into the Wild aims for an unfashionable grandness of gesture. But this doesn't leave much room for analysis. McCandless remains distant, infuriatingly literary and chipper. While Emile Hirsch is forceful and engaging, his golden-boy looks exude pampered confidence and an unformed personality. The film's most telling, and most frustrating, image is the photograph that ends it, a portrait of the real Christopher McCandless during his fatal Alaskan sojourn. His gaunt, bearded, confident face hints at a complexity that neither Hirsch, nor the film, begins to approach.

Further reading 'Into the Wild' by Jon Krakauer (Pan Books, £7.99)