EVER SINCE 1971's "The Last Picture Show," Jeff Bridges has been a workhorse of 100 percent credibility, class and magnificence. Yeah, I know, I'm holding back. But who doesn't like the guy? He's all Clydesdale, carrying entire, ordinary movies along with an affably effortless air. You feel like you know him and that he'd nod his wonderfully handsome horse face at you if you crossed paths in the street.

That talent for pulling along less-than-magnificent films and making them seem better is snortingly evident in "The Door in the Floor." Based on the first section of John Irving's novel "A Widow for One Year," it's a highfalutin drama about East Hamptons angst, lost children and "Summer of '42" sexual fantasy that splashes around in shallow tidal pools of cliche and familiarity. You feel like you've seen or read this business somewhere else -- in some cases, in books Irving has written. And yet, Bridges dutifully takes charge of any scene he's in; he makes a less-than-appealing character seem tragically princely, a man with noble whims and wrongheaded passions.

He's Ted Cole, a children's book writer and illustrator whose marriage has gone to hell, a randy fool with gusto and a heart. The reasons for the dissolution began with the two children Ted and Marion (Kim Basinger) lost recently to a car accident. But they continued with Ted's incurable philandering. The writer has a thing for saucy mother-and-daughter combinations. He persuades them into posing nude for innocently erotic (he talks a good game) drawings. Next thing they know, Ted's seducing the daughter (until she runs off to college), then the mother.

When aspiring writer Eddie O'Hare (Jon Foster) offers himself to Ted as a gushingly eager intern for the summer, he gets that terrible thing he wishes for: to sit at the feet of a presumed master. He soon realizes the real business of Ted's life: trouble with women. The writer trades parenting duties with Marion as they raise their 4-year-old daughter Ruth (the young Elle Fanning, who's given to obnoxious screaming). And he's currently hitting on the emotionally suggestible Mrs. Vaughn (a bravely naked Mimi Rogers) for nude poses and passionate quickies. Eddie's responsibilities include driving Ted to their assignations.

In this movie's heavy-handed scenario, Eddie is learning about Real Life. And since this is a) summer, b) at the beach and c) there's a sexy, emotionally wounded woman hanging around the place, Real Life will also mean initiative sex for the virginal lad. He develops an instant, time-honored young-man's crush on Marion. And when she catches him doing things he shouldn't with her personal effects, one thing rapidly leads to another. In no time at all, Marion's bringing him into the sexual fold with deer-in-the-headlights serenity.

Filmmaker Tod Williams, who made the offbeat and genuinely charming "The Adventures of Sebastian Cole," tries to force a sort of tender clumsiness between them. But it's just clumsy. And the predictably Oedipal recriminations that follow when Ted finds out about their relationship turn the movie into little more than tony melodrama -- the pleasing images courtesy of cinematographer Terry Stacey.

Bridges can't be a whole movie. But he's the main reason to watch. If this movie had risen to the occasions he demands, if it had attempted to probe any of its issues with more than skin-deep vigor, the film could have been finer. As it is, "The Door in the Floor" is just another minor highlight in Bridges' long and estimable career. And thank goodness, this horse still has a long way to go.

THE DOOR IN THE FLOOR (R, 111 minutes) -- Contains obscenity, sexual content and graphic images. Area theaters.

Jeff Bridges and Elle Fanning star in Tod Williams's "The Door in the Floor," based on a John Irving novel.