When John Hughes is credited as the writer-director of a movie, I'm never sure whether we're in for something as hilarious as "Planes, Trains & Automobiles" or something as flat as "She's Having a Baby."

"Uncle Buck" falls into the latter camp.

John Candy, virtually reprising his "Planes & Trains" character of a well-meaning but obnoxious slob, is the title character, a ne'er-do-well gambler whose girlfriend of eight years, Chanice (Amy Madigan), owns a tire dealership.

Chanice is trying to get Buck to settle down, but he can't make the commitment. She just about has him accepting a job in her tire shop when Buck gets an emergency call from his brother. The brother asks, against his wife's better judgment, that Buck come and babysit their three kids in the suburbs for a week.

The kids are a trio, elementary-age Maizy and Miles (Gaby Hoffman, Macaulay Culkin) and troubled teen Tia (Jean Kelly). The younger kids are amiable cuties, but Tia is a surly, unhappy wiseacre who hasn't adjusted to her parents making her move to a new town. Since both her parents work, she constantly makes cutting remarks to make them feel guilty about neglecting their children.

Mom is obviously hurt by these comments, and she and Tia have apparently been estranged for some time. But Dad just smiles as if nothing's really the matter, when it's apparent he should be reaching out to his daughter.

Soon Uncle Buck arrives and immediately wins over the little ones. Tia, however, is as nasty as she can be, despite Buck's efforts. She also has a "rocker" boyfriend named Bug (Jay Underwood) who makes sexual advances, and, of course, Buck's warnings about him only push Tia closer to Bug.

All of this sounds like pretty serious stuff — and it is. But there are lots of wild comedy scenes in "Uncle Buck," such as Buck's noisy, dilapidated car; Miles grilling of Buck, a la "Dragnet"; Buck confronting a school counselor about Maizy's being too "dreamy"; etc. But there is a dark side, as well.

The result is some very funny lines of dialogue and a few hilarious sight gags, but the more dramatic moments seem too stark in their seriousness. There's nothing wrong with blending comedy and drama, but Hughes doesn't give us any transition time to lead us into the highs and lows.