Fiction: Murder in the very first degree

Murder, always ghoulishly fascinating but - let's face it - extremely rare, infests a sickening and increasingly disproportionate amount of our literature, film and television. Margaret Atwood's fat, dauntingly quote-peppered novel claims to be based on the life of the "celebrated" Grace Marks, convicted of murder in 1843 at the age of 16. So I entered it with the sinking feeling that I was in for yet more of the above: a historical, fact-based, murder thriller.

I emerged, a day or two later, altered, in awe and bereft. Good fiction always transports, but this was something quite other; a novel so exceptionally dense and alive that "reading" seemed an inadequate description of the profound experience of being on its landscape and among its characters. Come the last page, this was a world I could not bear to quit.

Alias Grace is a sensuous, perplexing book, teasingly difficult to pin down: at once sinister and dignified, grubby and gorgeous, panoramic yet specific. It is almost a love story and a page-turner, but the theme which emerges most strongly is bald, gratuitous curiosity; the human impulse to bite down to the kernel of another's soul, to gather facts - and then arrange the facts to suit our own flawed needs and expectations.

Grace was convicted, along with a man called McDermott, and imprisoned for life in Toronto. She escaped hanging only because she was so young and (her lawyer pleaded) of dubious sanity and intelligence. When Atwood takes up the story, the girl is still incarcerated (and has been for eight years) but her calm, likeable behaviour has won her a daytime servant's position in the prison governor's household. She is 24 when Simon Jordan, a young and progressive doctor specialising in mental health, decides to spend time talking to her. Fascinated by the disparities in the various newspaper and journal accounts of the infamous trial and confessions, he wants to understand what lead her to commit the crimes - if indeed she did commit them, for Grace has always claimed to have no memory of the grisly events that led her to a cell.

Here the novel divides into two equally absorbing strands. Grace recounts to Jordan her life, from her harsh childhood emigrating from Ireland to Canada, right through to when - and the sense of imminent doom is flawless - her employer and his housekeeper (who was also his mistress ) were found murdered in the cellar.

Meanwhile, dovetailed with this narrative, Jordan returns each evening to grim, bachelor lodgings, a sexually predatory landlady and a mother who writes constantly urging him to marry. As the conversations between doctor and patient grow and flower, an understanding and respect also blooms between them. Each finds in the other a space, a window, a break in the claustrophobic pattern of their lives. Grace recognises that Jordan is the first man ever to treat her with intelligence and decency; he is unsettled to discover that she is the first woman he has ever enjoyed talking to.

But Grace's account of her part in the murders remains vague. Chased, harassed and threatened by men all her life (though still, according to her story, a virgin) she tells how, paralysed by fear, she helped McDermott hide the bodies and escape. And her traumatised mind blotted out the rest. But can we believe her? Reluctantly, Jordan agrees to allow his patient to be hypnotised before an invited audience. The resulting scene is jumpy, sinister and perplexing.

To reveal more would be unforgivable: this is an intensely suspenseful book. Suffice it to say that, halfway through, I was unnerved to find I had developed questions, frustrations and wilful interpretations of my own. For Atwood's sublime achievement is the extraordinary personal and intoxicating lure of Grace's voice. The girl is practical, honest, dignified, occasionally snobbish, often prudish, endowed with all the arrogant moral energy of the Fundamentally Good. But every so often this pure, calm voice falters, trips, shifts - taunts with (can it be?) sexual knowingness. And the hackles rise.

Our only hope of a control is Jordan - an awkwardly real, intensely sympathetic creation. With all the idealism of the intelligent, he longs for love (and sex), yet finds none in the flimsily attractive women who surround him. A moral crusader isolated by his own stubbornness, he finds himself taunted by Grace's availability and vulnerability. He wants her psychologically probed and then vindicated. Or does he just want her?

And behind all this, Atwood's imaginative control of her period flows, irresistible and superb. She gives us dark rooms and filthy lodgings, greasy chicken joints and laudanum, sunny orchards, long gravelly drives, a cheesy summer kitchen, dust bunnies under the bed, pork fat, saving soap, fireflies, sweat, bad teeth, a smudge of hair on a woman's cheek. I don't think I have ever been so thrilled, so shamelessly manipulated, so daunted by a piece of fiction. Atwood has pushed the art to its extremes and the result is devastating. This, surely, is as far as a novel can go.