BOOK REVIEW / A character assassin in heels: Malice in Wonderland: Helen Birch reads Margaret Atwood's spiky new novel: The Robber Bride - Margaret Atwood: Bloomsbury, pounds 14.99

ZENIA is a bitch: Twenty-four carats of motiveless malignancy, hard, brilliant and beautiful as a diamond. She makes men drool and women bitter. Her trick is to defuse the latter with whatever it takes to get them on her side - sympathy, vulnerability, sass - to captivate their men and then vanish into the ether, leaving those whose lives she has wrecked to wonder what hit them. She is, of course, an expert fabulist too, reinventing herself with each new drop-dead dress, a wild card in the novelist's deck.

The notion that women can be pretty awful is an idea Margaret Atwood delights in. Not for her the saccharine of sisterhood; she knows what women are capable of - to some extent they enjoy disliking, manipulating and taking revenge on other women - and in her novels she has duly delivered to her readers a succession of figures they can stick pins into. With Zenia, though, she has surpassed herself; through Zenia she lets rip in zinging, thrilling prose; she has created a force that drives the reader through nearly 500 pages of sometimes long-winded exposition.

The novel opens with Zenia's funeral, attended by three of her erstwhile victims. There's Tony, the military historian, Charis, aka Karen, the hippy dippy one who sees auras and spouts New Agey nonsense with the bug-eyed intensity of Shirley MacLaine. Then there's Roz, the rich, smartarsed businesswoman. Shortly afterwards, when the three meet up for one of their monthly lunches, Zenia reappears, airbrushed pin-up made flesh once more.

From here, Atwood takes us on a tour of each woman's past. For Zenia to have power, her conquests must make sense. Cue childhood flashbacks in which we learn that each woman has in some way been abandoned, abused or badly mothered so that each is disarmed, her armour as vulnerable as skin. And Zenia, a truly modern combatant, has done her research on her victims. Some of this is plausible enough; Tony and Charis fall in the Sixties and early Seventies respectively - pre-feminism, before the word self-determination really applied to women. Hence their slavish devotion to weak, faithless men. But with the story of Roz, Atwood stretches credibility. It is the late Eighties when Zenia comes calling on Roz, long after Roz has witnessed the devastation Zenia has wreaked upon her friends, after she has taken control of her father's business and become actively involved in the women's movement. Here, Atwood's liberalism - the beginning (childhood) explains the end (adulthood) - wears a little thin. Although Zenia reflects Roz back to herself as powerful and knows which button to press, you can't help wondering why she appears to have learnt so little from her adult experiences.

None the less, there is real vigour in these stories, and Atwood relishes the opportunity to present the same events or conversations from three different points of view, each of which tells us something about the nature of the reality they purport to represent. Indeed, where the novel works best is in its subtext - the necessary fictions we all invent to make our lives signify something.

Tony, who studies war, structures the world like the model battleground she has built in her basement, moving troops around, testing outcomes, controlling events by writing them up as linear history. The messy stuff she holds in check by a backwards language perfected when she was a child. This is 'a seam, it's where she's held together, it's where she could split apart'. Charis, whose daftness Atwood handles with gentle irony, affirms what we long suspected, that from Wicca women to Germaine Greer's embracing of the menopause, women's attraction to white witchery is simply one response to powerlessness. And, Atwood seems to say, if it works, why not?

With Roz, she has most fun. Roz goes shopping and wears her make-up and her wit like warpaint. Atwood exploits these contrasts to great effect. As Tony earnestly explains the background to the impending Gulf war - 'It was decided as soon as Saddam crossed that border. Like the Rubicon' - Roz is dreaming up a new line of lipsticks, 'a great series of names, names of rivers that have been crossed, crossed fatefully; a mix of the forbidden and of courage, of daring, a dash of karma'.

At other moments Atwood uses her characters to highlight an individual's uniqueness, the idea that however well we think we know someone, we can never get inside their heads. 'Sometimes,' Tony muses, '(she) would like to take Charis by the lily-white hand and lead her to the piles of skulls, to the hidden pits filled with bodies, to the starved children with their stick arms and ballooning stomachs . . .' For Charis, though, 'the words (of war) are pictures and then screams and moans, and then the smell of rotting meat, and of burning, of burning flesh . . .'

The trouble with this approach is that too often, Atwood's characters become little more than the sum of their peculiarities. At no point do we feel really engaged by them. Which is why Zenia, as evil incarnate, a facet of each woman's fantasy, exerts such power over the narrative. Her motivelessness and the sheer, unexpurgated spite she unleashes at the end contains truths that the others, unlike the reader, are too dim to realise. In a brutal way, she has done each of them a favour, and so Atwood, egalitarian to the end, allows her to be reclaimed for the sisterhood, detoxified in death. Throughout The Robber Bride, you long for Zenia to upset Atwood's steadfast equilibrium. But that would be a different book.