How far would you go to save your child’s life? How far should you go? Those are the questions posed — and largely ducked — in this film based on the best-selling book, My Sister’s Keeper, by Jodi Picoult. The New York Times recently said that in Picoult’s books, which often focus on “terrible things” happening to children, “he assault on any individual family is typically mounted from angles multiple and unforeseen.”

The “terrible things” here are inspired by a real-life story. Sara (Cameron Diaz) and Brian (Jason Patric), learn that no one in their family matched their daughter well enough to be able to donate bone marrow or blood cells she needs for cancer treatment. So, they decided to have another baby, one specifically genetically tweaked to be able to provide her sister with healthy cells, starting with the blood from her umbilical cord. As she says, most children arrive by accident, but she was designed to be born for spare parts. At age 11, having spent her entire life being pricked and prodded and now being asked to give up a kidney, Anna (Abigail Breslin) hires a lawyer (Alec Baldwin) to sue for “medical emancipation,” to get permission to stop.

Solomon had to choose between two mothers who both claimed the same baby and he was not related to any of them. But Sara and Brian must choose between their daughters, and they are so desperate to save the one who is sick that they cannot admit to themselves the damage they are doing to the one who is well. The ones who are well — there is also a son who is so overlooked that he sneaks back into the house after being out all night only to find that no one noticed.

Director Nick Cassavetes (“The Notebook”) wisely changed the jarring ending in the novel and is very effective in conveying the matter-of-fact mastery of the details of the symptoms and treatments, a touch of authenticity that is in sharp contrast to the one-dimensionality of the characters. He overdoes the pop songs on the soundtrack, though, with so many montages it feels like a music video punctuated with brief scenes of family anguish. But Picolt insists on allotting tragedy to every character as though she is dealing cards. And she undermines the power of the story and its themes with a syrupy overlay that distorts the issues so that the result is more gooey than dramatic. Cinematographer Caleb Deschanel composes exquisite images. But they add to the sense the film does exactly what it says it does not do and ties everything up in a mode that is just too neat and convenient instead of engaging in a forthright and honest way with the issues and the characters. That just rings hollow and ultimately disrespectful to the conflicts it purports to portray.

Patric, who should be in more movies, is outstanding as Brian. The look in his eyes as he watches his daughter go on a special date is heart-wrenching. Diaz, in her first role as a mother, is fine in the quieter moments but never reaches the ferocity that is at the heart of the story. As the sick girl, Sofia Vassilieva is luminious and wise. But the best moments on screen come from Joan Cusack as the judge. Every tiny gesture and look is searingly authentic, a bracing dose of reality in the midst of the gooey saints all around her.