Kids, eh? Feed them, clothe them and put them a trampoline in the back garden, but ask them to donate one lousy kidney to save a dying sibling and what do you get? A lawsuit.

That's the situation Sara and Brian Fitzgerald (Diaz and Patric) are faced with after their youngest child Anna (Breslin) marches into the office of hotshot attorney Campbell Alexander (Baldwin) demanding 'medical emancipation' from her parents.

They have only themselves to blame. See, Anna's conception was less an act of love than a matter of genetic necessity.

But having spent the best part of eleven years being skewered, sliced and diced to provide healthy, compatible body matter for her cancer-stricken older sister Kate (Sofia Vassilieva), Anna has had enough.

Sara (bolshy ex-lawyer, used to getting her own way) is appalled, whereas Brian (strong, sensitive fireman, used to letting the wife have her own way) can see the girl's point.

Strangely, Kate (sick, tired, used to being sick and tired) and brother Jesse (artistic, dyslexic, used to being overlooked) apparently don't have an opinion.

Exposing the film's bookish roots, director Nick Cassavetes fades in and out of the family's traumatic past while all the characters bar the parents (and Aunt Kelly - what's she all about?) get to narrate their side of the story.

If earnestness was bone marrow, the entire cast would be universal donors. Sadly, their work is undone by Cassavetes and co-writer Jeremy Leven who skirt around the moral quandary at the story's core and lapse into melodrama at the drop of a syringe.

Kate's romance with a cool chemo-recipient ends when he is given one of the best reasons ever for not calling after sex, and the ultimate showdown in court – presided over by Joan Cusack's emotionally fragile judge - descends from revelation into ridicule.

This is grown-up drama for not-quite-grown-ups, avoiding any real nitty-gritty by rinsing away every eruption into the sick bucket with a solution of golden-hued mawkishness and schmaltzily anaesthetic tunes. And there's you thinking they'd forgotten to include Amazing Grace.

With issues like these covered with more bravery, brevity and credibility every week in class TV acts from ER to Boston Legal, only the performers give good reason to see it through.

As the kind of mother who'd have a child simply to save another, Diaz's head-shaving episode says less about her character than her commitment to the role.

Her efforts are matched across the board, but surpassed by Vassilieva who stands out amongst her higher-profile peers with a performance remarkably free of showboating and self-consciousness.

But when the parts add up to more than the sum, it's no keeper.

Elliott Noble