What do you do with a movie that is thoughtful, and contains some wonderful acting, but keeps making you think that the main character is a fool?

Do you accept his fatal errors and simply follow the story? Do you, like other characters in the film, feel great affection for the young man, even as he heads into disaster? Or does the movie ultimately lose you, because you have spent more than two hours on a path that will lead you into despair and loss?

These are questions nagging at me ever since I saw Into the Wild, writer-director Sean Penn's engrossing but frustrating adaptation of Jon Krakauer's book of the same name.

The 1996 book attempted to understand Christopher McCandless, a wealthy and idealistic young man who thought he could live for an extended period in the wilds of Alaska. He was wrong, and starved to death in August 1992.

Krakauer tried to get at the heart of McCandless by looking at other doomed explorers, and at his own attempt at a similar adventure. He talked to McCandless' family, he visited places where McCandless had traveled. Even as he sat in the place where McCandless died, Krakauer thought that ''his essence remains slippery, vague, elusive.''

But even as Penn's movie follows the arc of McCandless' waning years (with some dramatic embroideries), it has some clarity about the wanderer, a view that will resonate with any parent who has worried about a grown child, and with any young person who has yearned to break free from his parents' way of life.

Into the Wild is a story about families, both real and cobbled together, and about people's common longing for companionship. McCandless might have felt that longing in his final days but it was too late to do him any good.

Indeed, it is longing that drives two of the film's most glorious performances, by Catherine Keener and Cleveland's own Hal Holbrook, as well as a marvelous moment by William Hurt.

Emile Hirsch plays McCandless, whom we first see as he is graduating from Emory University, poised for a new life. His parents (played by Hurt and Marcia Gay Harden) are expecting him to continue his education. Instead, without their knowledge, he gives away almost all of his savings and, penniless, goes off in search of a world free of the things he hates in his parents' comfortable lives.

The movie then follows his journeys down rivers and across deserts, picking up the occasional job and bonding with people he meets along the way. Hirsch's fresh-faced air of innocence and seeming openness appear to invite not only love but protection, whether it's from Keener's aging hippie, a somewhat shady businessman played by Vince Vaughn or the rough-hewn former military man played by Holbrook.

Because McCandless is so single-minded about his travels, especially his Alaskan dream, he repeatedly rejects the wisdom and love that others offer him. This is not new, since he has also cut himself off entirely from his parents and his beloved sister (Jena Malone). But it makes him seem offhandedly cruel, hurting those who offer him powerful emotional gifts.

And that is why I think him a fool.

And that is why, as McCandless faced death, it was not a more painful experience for me. He had chosen his direction, even with all its dreadful possibilities. I felt far more for his family, extended to include Keener and Holbrook, who did so many right things, only to suffer loss because they could not persuade McCandless.

Penn's direction is very good, though his script is at times overdone, especially in a voiceover by Malone. The supporting cast is extraordinary. The movie haunts me. But I'm still left troubled by the man in the middle of it.