The picture slyly sneaks up on you. For the opening thirty minutes, it is understandable to question where exactly the movie is going. The random flashbacks at the onset do not have the sort of effectiveness Steers might have been going for because we are immediately asked to get involved in a family's dysfunction when we have not properly met them in the present day. There is also an episodic nature to other early moments, as 17-year-old Igby (Kieran Culkin), a disaffected, misunderstood youth, does everything in his power to be kicked out of one high-profile school after the next. Born into a privileged life but consistently rebelling against the norm, he is an embarrassment to his snooty, domineering mother, Mimi (Susan Sarandon), and straight-arrow older brother Oliver (Ryan Phillippe). Igby also has a father, Jason (Bill Pullman), now a resident at a mental institution following a nervous breakdown who has been out of the picture since his childhood.

With the appearance of two more key characters, "Igby Goes Down" has a sudden transformation from a seemingly aimless slice-of-life into a sharply focused and genuinely enthralling one. Off to yet another affluent military school that Mimi insists he attend, Igby makes a sudden detour to New York City and hides out in a loft rented by Rachel (Amanda Peet), the sometime-mistress of Igby's godfather, G.H. (Jeff Goldblum). He also meets, and is immediately smitten by, Sookie Sapperstein (Claire Danes), a sophisticated, slightly older Bennington student who talks as if she has the whole world figured out, but is just as confused as he. Sookie likes Igby, too, mainly because she thinks he's "funny," but their romance is cut short with the unwelcome appearance of Oliver.

One of the most appreciative qualities "Igby Goes Down" exhibits is an avoidance of tying the plot and characters into neat, tidy bows by the conclusion. People come in and out of the film without warning, as actual people do in the real world, and there are no easy answers or solutions to soothe their individual hardships. At the center of it all is Igby--clearly modeled after Holden Caulfield in J.D. Salinger's brilliant novel "The Catcher in the Rye"--who hides behind sarcasm as a way of dealing with his inutterable confusion to what he wants and where he is going in life. It is never clear if the alienation and contempt he feels for his family has grown from his inability to understand them, or from just not wanting to.

In the emotionally demanding title role, Kieran Culkin (2002's "The Dangerous Lives of Altar Boys") gives an eye-openingly brilliant performance that stands, easily, as one of the best of the year. He carries the entire film, and is vital in turning the difficult Igby into an accessibly sympathetic, three-dimensional protagonist.

Culkin is ably supported by a top-notch supporting cast that brings the rest of the ensemble to life. In a gratifying return to the big screen after a three-year absence, Claire Danes (1999's "Brokedown Palace") is simply incendiary as Igby's radiant object of desire, Sookie Sapperstein. In many ways, Sookie is just as unforgettable and complicated a character as Igby, as it becomes increasingly obvious she is less self-assured than she outwardly carries herself. Danes does wonders with this marvelously realized part.

Amanda Peet (2002's "Changing Lanes") is another standout, blessed with many great scenes as her Rachel is subtly revealed to have far more problems than she initially projects. Susan Sarandon (2002's "The Banger Sisters") goes against-type to indelibly play Mimi as a selfish shrew who cares more about her reputation than her own children, coming close several times to an epiphany she never quite reaches. As Igby's mentally ill father, Bill Pullman (2000's "Lucky Numbers") is insufferably tragic with only a few minutes of screen time. As is usually the case with any movie he appears in, Ryan Phillippe (2001's "Gosford Park") is the sole weak link. Phillippe is a blandly vacant actor that almost always rubs me the wrong way, and his turn here is no exception.

Unlike the majority of motion pictures that get off to a rousing start only to sputter out by the finale, "Igby Goes Down" only gets better as it goes. As uneven as the first act is, the third act is just as remarkable. Through the course of Igby's journey, he is never offered any comforting solace as to where the rest of his life is going to take him, and there is an undeniable richness in the way director Burr Steers says this without feeling the need to spell it out. The concluding moments, scored to Travis' cover of The Band's classic song, "The Weight," are, especially, unexpectedly powerful, and director Steers rightfully earns every one of them.