'My Sister's Keeper' Just Can't Keep Its Weepy Stories Straight

"My Sister's Keeper," the much-anticipated adaptation of the novel by cult favorite Jodi Picoult, has to do with emancipation, a theme that the movie itself unwittingly plays into. At least two perfectly good movies fight to break free within this busy, oddly shaped weepie: one a peppery, provocative legal thriller, the other a mother-daughter melodrama worthy of Joan Crawford and Lana Turner at their most Gothically self-sacrificing.

If director Nick Cassavetes had decided to make just one of those films, "My Sister's Keeper" would have provided a nifty piece of early summer counterprogramming to the bigger-louder-dumber fare on offer on most screens. Then again, he most likely would have been pilloried by Picoult's fans, who gobble up books whose trademarks are complicated ensembles of character-narrators, convoluted plots, meticulously staged coincidences and lurid visions of parental agony.

In that regard, Cassavetes -- best known for the 2004 hit romantic drama "The Notebook" -- can be thanked for reining in the most outlandish aspects of "My Sister's Keeper." He's succeeded in creating an adaptation that, while departing dramatically from such key elements as the book's ending, will no doubt please fans in need of a good cry, no matter how manipulatively the tears have been jerked.

If "My Sister's Keeper" has a central character, it would be Anna (Abigail Breslin), an 11-year-old girl who was conceived by her parents, Sara and Brian (Cameron Diaz and Jason Patric), in order to harvest umbilical cord blood, bone marrow and various organs for their daughter Kate (Sofia Vassilieva), who suffers from acute promyelocytic leukemia. As "My Sister's Keeper" opens, Anna marches into the office of an aggressive Los Angeles attorney named Campbell Alexander (Alec Baldwin), demanding to be "medically emancipated" from her parents. Kate is in renal failure, and Anna doesn't want to donate the kidney she was specifically bred to give up.

It's a thorny ethical debate rife with dramatic potential, and as long as "My Sister's Keeper" stays with this fascinating, disquieting issue and its effect on the family, the movie toggles smoothly between intellectual arguments and rank emotionalism. This is, after all, a movie whose early scenes include a young girl being held down for a spinal tap, and later coughing up blood with the grim heroics of Camille. Anna's encounters with Alexander, and later with a judge played with twitchy sharpness by Joan Cusack, keep mawkishness gratifyingly at bay. (Par for Picoult's course, even these supporting characters come with their own plot twists that could have been engineered in the same petri dish as Anna.)

But just when "My Sister's Keeper" looks like it might be an absorbing, unusually prickly break from sentimental tradition, the action shifts from Anna's story to Kate's, when she meets a fellow patient (Thomas Dekker) and falls in love. It's an undeniably affecting sequence, given added appeal by a terrific performance by Dekker, but it represents one of several tonal shifts that make "My Sister's Keeper" an ever-widening shaggy dog story (come to think of it, it even features a shaggy dog). Awkward, too, is Cassavetes's reliance on music cues to sell the movie's swirling emotions. After countless montages of people blowing bubbles on trampolines or gamboling attractively on the beach, one longs to remind the filmmakers that a series of scenes set to wistful pop songs does not a movie make.

For their part, Breslin and Vassilieva acquit themselves beautifully in emotionally and, in Vassilieva's case, physically demanding roles. Evan Ellingson, as their largely ignored big brother, Jesse, makes the most of an otherwise marginal character. Patric, playing the world's richest firefighter, seems to float passively throughout the proceedings, although that's probably appropriate for a character who can't bring himself to tell his cancer-riddled daughter that yes, she is pretty.

Even though "My Sister's Keeper" is nominally Anna's story, the real center of the action is Sara, played by Diaz with a spiky, careworn absence of vanity. Diaz has made dramatic bids before, in "Being John Malkovich" and "Things You Can Tell Just by Looking at Her." But perhaps a moment of silence is in order to recognize the fact that one of Hollywood's most delectable pop tarts is now playing the mother of teenagers (meaning I must be 100 years old). So passes the glory of the world -- yet another theme of one of the many movies vying for pride of place in "My Sister's Keeper."

My Sister's Keeper (109 minutes, at area theaters) is rated PG-13 for mature thematic content, some disturbing images, sensuality, profanity and brief teen drinking.