NOTHING quite illustrates the absurdity of the Nobel Prize for Literature as the fact that Toni Morrison is its most recent American winner.

She received her bouquet in 1993 when she was 62 and already the author of such celebrated novels as Song of Solomon and Beloved, which won a Pulitzer Prize. Once bizarrely described as the "DH Lawrence of the black psyche", Morrison, like her contemporary Philip Roth, is a mistress of the public novel, ever eager to tackle hot topics such as race and sex in a manner that, at her best, is both timeous and timeless. Her style, meanwhile, in contrast to Roth's, is rooted in biblespeak and the testimony of her characters is relayed in prose that is at once conversational and poetic.

Morrison prefers to tell her stories in short declamatory statements and sentences, plunging her readers into situations without preamble. Another writer with whom she has often been compared is Gabriel Garcia Marquez, which is not as far-fetched as it might seem. For me, however, her bloodline encompasses James Baldwin, Ralph Ellison and, most conspicuously, William Faulkner, whose ability to withhold and release information she has inherited. When you read a novel by Toni Morrison it cannot be read lazily for she is disinclined to hold anyone's hand. You need to find your own way into it and out of it.

God Help the Child takes its cue from the Billie Holiday song. It is a short book of 178 generously spaced pages and may be read at a sitting. While it contains elements of magical realism - as it progresses its main character, Bride, inexplicably loses her body hair and her "flawless" breasts, then, in an incendiary scene at the novel's climax, regains them - it is relatively straightforward, even traditional. Initially told in a series of pacey chapters by a handful of narrators, at its core is a preternaturally black woman who has overcome hopeless odds to become a success in the cosmetics industry.

Originally named Lula Ann Bridewell, Bride was an instant embarrassment to her mother, Sweetness, on account of the colour of her skin. Even among black people, there was - probably still is - a skin hierarchy. "The lighter, the better" is Sweetness's mantra. Her mother was pale-skinned and could pass for white when buying hats or using the ladies' room in department stores. But when she got married there were two Bibles in the church, one reserved for Negroes, the others for whites. "My mother was housekeeper for a rich white couple," Sweetness recalls. "They ate every meal she cooked and insisted she scrub their backs while they sat in the tub and God knows what other intimate things they made her do, but no touching of the same Bible."

Ostracized by her own family, Bride has made her way in a world where looks are paramount. Rather than camouflage her blackness, she wears white dresses in order to emphasize it. In my mind's eye, I had Naomi Campbell, and Morrison may have had too. But however successful Bride has become she is burdened by a lie she told when she was an eight-year-old which resulted in a teacher named Sofia being convicted of child abuse and sentenced to fifteen years. Desperate to right a wrong and seek forgiveness Bride welcomes Sofia on her release from prison but does not get the response she expected. That, and the sudden disappearance of her lover Booker, who has a body and a past - his younger brother Adam, it transpires, has been tortured and murdered by a paedophile - that is at least the equal of hers, is what gives God Help the Child its dramatic dynamic.

It is perhaps wise not to dwell too closely on the degree to which Morrison's novel is reliant on such coincidences. Suffice it to say that it is not only the Victorians who depended on the device. More worrying, however, is why Bride is determined to find a man who has left her so abruptly and about whom she knows so little other than that he reads books and is a demon lover. As the novel progresses we learn more about Booker, not from him but through a third-person narrative which smacks of convenience rather than adroit plotting. He is an angry, intelligent, occasionally violent young man who has become estranged from the rest of his family because they want to move on from the death of Adam while he wants to memorialize him.

There is a lot going in this novel, arguably too much. Children and how they are mistreated is at its core. It seems that Philip Larkin was on the right track when he wrote, "They f*** you up, your mum and dad./ They may not mean to but they do." But they're not the only ones who're culpable. Morrison gives us children who've been abandoned, misled, mentally damaged, routinely abused, murdered. Occasionally, there is a glimmer of hope, of adults acting charitably and responsibly, but that's the exception, not the rule. This ought all to be emotionally wringing stuff but too often the writing is off-kilter and strikes a jarring note. For instance, Morrison offers streets "dappled" with homeless veterans and a dirty mattress "sporting" dried blood. Such mood-altering verbs go some way to explaining why God Help the Child packs a much less powerful punch than might be expected of one of fiction's heavyweights.

God Help the Child, by Toni Morrison, is published by Chatto & Windus, priced £14.99