"Stepmom" has all the right ingredients for a good drama, including the presence of a talented and attractive cast and a filmmaker with a proven track record for this kind of material ("Mrs. Doubtfire" director Chris Columbus).

But all that still isn't enough to save this sappy and surprisingly downbeat movie, which is credited to three separate sets of screenwriters.

Frankly, the film feels like it came from even more writers. Plotwise, "Stepmom" goes off in so many different directions that it can't possibly tie up all the loose ends satisfactorily. As a result, the film feels like a Lifetime cable reworking of "Terms of Endearment," with better-than-TV production values.

Julia Roberts stars as the title character, career-obsessed fashion photographer Isabel Kelly. Isabel is dating a much-older, divorced attorney, Luke Harrison (Ed Harris), but his children — 12-year-old Anna (Jena Malone) and 7-year-old Ben (Liam Aiken) — aren't too thrilled about the new woman in his life.

Nor, for that matter, is his ex-wife, Jackie, who resents Isabel's half-hearted attempts at parenting — especially when she briefly "loses" Ben during a working trip to Central Park.

But the two women are forced to reconcile their differences when Jackie is diagnosed with terminal cancer. This forces her to share the children with Luke and Isabel, who have decided to make their relationship more permanent. The only question is whether the children will accept the new working (and living) arrangements.

One major fault with the film is that this material has been done to death — and far better. Also, the relationship between Roberts and Harris isn't believable, partly because he's on-screen for such a brief time. And most of the attempts at humor are either extremely forced or appear to be afterthoughts.

Still, the two leads are terrific, especially Sarandon, who works wonders with her underwritten character. In fact, the performances are almost universally excellent, save Aiken, who spends too much time mugging for the camera.

"Stepmom" is rated PG-13 for profanity, use of vulgar slang (including some sexual terms), drug use (medicinal marijuana) and some violent roughhousing between two children.