Living it up on mom's credit card

You don't expect a comedy to begin with two boys trying to poison their mother.

But "Igby Goes Down" starts just this way, and pulls it off to surprising effect – leaving viewers in the unexpected position of laughing at death.

So the tone is set for this alluring and sometimes unsettling film, which traces the coming of age of the blue-blooded yet rebellious Igby – who is played by Kieran Culkin, just one of many recognizable names in the cast.

From here, the movie rewinds to explain how Igby and his older brother, Oliver (Ryan Phillippe), could possibly do such a thing.

The explanation starts with Igby, who has worn out his welcome at practically every East Coast prep school, being shipped off to a military academy by his mother (a convincing Susan Sarandon).

Igby can't stand his new quarters, especially after a ring of boys roughs him up, and he longs to wriggle out of the life his mother has decreed.

He sees his chance when he meets a mistress of his godfather's. With the help of Mom's credit card, Igby lands on her doorstep in New York – and enters a world of misfit characters alien to a privileged lifestyle.

While Igby's adventures take some serious turns, it's on the whole an entertaining ride. But in the end, the movie seems to be only that, with not much of a meaningful destination.

Indeed, what Igby has gained from his coming-of-age experiences could have been more distinctly focused. His exposure to drugs and sex, for example, is too clichéd. While his relationship with his increasingly ill mother culminates in a much more cathartic moment, even this could have been probed further.

Viewers will expect more from a movie with such a talented cast, which also includes Jeff Goldblum, Claire Danes, Bill Pullman, and Amanda Peet.

Still, its uncommon blend of the serious and funny should keep viewers engaged – and maybe even give them a newly tempered perspective on growing up.

• Rated R; this movie contains foul language, sex, and drugs.