Books: When everything matters all the time

THE FAMILY - with its idiosyncratic blend of passion and poison - looms large in modern fiction, but (oddly, given how many of us have them) sisters do not. I can think of Jane Smiley's A Thousand Acres and Helen Dunmore's recent, edgy and discomforting Talking to the Dead, but otherwise it's hard to remember many modern novels which pivot on - or set out specifically to examine - this "group of disparate souls with a shared start". Anne Fine fills what feels like a surprising gap with her angry new novel.

Bridie is a social worker, the eldest of four "close" sisters. Her position in the family, her personality and (inevitably) her profession, mean that she is regarded rather grudgingly as the responsible one, the one who "keeps the family going" with her "schemes and plans". Heather - cool, hard, unmarried - works with money and parts with her time and emotional energy only when it suits her. Stella - who runs a gadget-perfect house in suburbia with lawnmower-fixated husband Neil - is, according to Bridie, "morally vapid". And Liddy - youngest, prettiest, most emotionally demanding ("to her people were soulmates or nothing") - is divorced with two young children. And now she's besotted with new fiance, George, who seems to be a very decent chap and is especially good with her kids.

But Stella hears some disturbing gossip about George. Back in Scotland, he was once up in court for child molesting. Stella tells Heather. Heather, true to form, does nothing. So Stella tells Bridie, knowing that she - social worker, "active listener", professional child protector - is too responsible not to act. She's right. Bridie convinces her sisters that Liddy must be told - and then pesters them until they agree to act.

Liddy - shocked, humiliated, disbelieving and furious - automatically (and fascinatingly, given it was Heather who actually made the phone- call) blames Bridie. And when Bridie turns to her sisters for support, she finds none. Stella and Heather, purged by the telling and now also happily absolved of blame, value a quiet life more than an open one. Quick to agree with Liddy that the rumour is probably false, they omit to say that they supported Bridie in her decision to tell. Bridie is duly ostracised, and outraged. And this is Fine's story: how unswervingly potent are our perceived roles within the family.

"I don't understand your family," says Bridie's husband. "I don't understand why everything has to matter all the time. Why you have to have all these feelings. I don't see why, once you're grown-up, people have to stay special because they're family."

These four, gloriously bland sentences bite at the novel's flinty heart. What are sisters worth if, in adult life, they don't want your tough love? Can you tell each other lies and still have enough in common to giggle on the phone together? And does "everything" have to "matter all the time"? Bridie, shocked and betrayed, concludes it does not.

But Fine is too subtle a writer to play goodies and baddies. If I've made Bridie sound blameless, then it's probably just that I'm a biased, control-freak of an eldest child. Bridie has all the routine emotional bossiness of a first-born: she's judgmental, secretly convinced of her moral superiority, quick to impose her vision of happiness-through-honesty on others' lives.

But her fury has consequences. Bridie uncovers a secret something she did not know, something no-one told her (well, they wanted a quiet life, didn't they?). Released at last from the constraints of good behaviour, released from the endless phone calls and arrangements, the baking cakes and lending equipment (these are sisters who live in each other's pockets), she suddenly has more time for her husband, her teenage sons - herself. "If she had known the virtues of detachment from the start, then she too could have floated all her life on this soft, easy and uncaring cloud." Bridie floats. But suffused with loss - and altered, indeed hardened by what she now knows - she plots her revenge.

Fine has thrust a dismaying picture of sisterly attachment and detachment in our faces. This is a perspicacious and terrible, wise and embarrassing novel: so much of it shameful, all of it true. Always easy with dialogue, Fine defines her characters so effectively by what they say, that the book bulges with the flood of brief conversations, each one more chilly and disheartening than the last.

Rightly, the tale throws up far more questions than it answers - in fact, I'm not sure it answers any. Just when you think you know where you are, a new possibility emerges and someone's position shifts. And just when Bridie seems on the verge of a kind of emotional stillness and peace, you glimpse the self-hatred simmering beneath. And shudder.