BOOKS: FICTION: In a Norte world

THE TORTILLA CURTAIN by T Coraghessan Boyle Bloomsbury pounds 14.99

CORAGHESSAN BOYLE has always seemed a flirty, unsatisfying talent. His yards of gaudy phrase-making and goofy satirist's subject matter - marijuana-farming in California, a cereal magnate's worship of enemas - have made him a dandy of a novelist: charming to book reviewers for brief encounters, but exasperating to readers in search of thematic commitment.

This time he has stopped smirking. The Tortilla Curtain comes with a stark photograph of chain-link fencing on the back. Boyle's concern is illegal immigration in America, and all the costs and tensions that this daily tide from Mexico to El Norte brings; beyond that, it is the condition of the great immigrants' nation itself.

Jack Delaney, a wealthy white Californian, drives his air-conditioned car over a penniless Mexican migrant called Candido. It's the same set-up as in Tom Wolfe's The Bonfire of the Vanities, but Boyle immediately enlivens it. Delaney is a "liberal humanist" with a carload of recycling, yet paranoid enough about crime and insurance - this is Los Angeles - to throw his bleeding victim a $20 note and drive off.

While Candido collapses in his makeshift camp with his pregnant teenage wife America, Delaney calms down nearby in the cool, tiled study of his Spanish Revival villa. He and his workaholic estate agent wife Kyra have moved to the mountains to find nature, and Boyle makes merry with their hypocrisies. Delaney writes a gushing nature column from behind their six-foot security fence; he scorns the "jerk in a crypto-fascist uniform" guarding the gates of their development, but feels safer because he's there.

As Delaney hikes and barbecues, Candido and America walk miles to work and warm up garbage scraps. Seeing California through their eyes is more of a challenge than mocking familiar sensibilities for Boyle (who lives in wealthy white Santa Barbara), but he manages it, vividly. Hulking, hostile Americans besiege them, cars scream by as they shuffle along freeway gutters - the central image of vast, "sealed in" vehicles threatening vulnerable flesh is potently deployed - and more predatory migrants harass them, too. A gang of bandits strips Candido at the border; an almond-eyed monster rapes America.

These crises are paralleled by a smaller set of problems in Delaney's life. His air-conditioned car is stolen. Kyra's pets are carried off by a coyote. While the gulf between their circumstances and the migrants' is kept clear with a series of mutually uncomprehending chance encounters, similar longings emerge. Both desire their "own private space", away from crime and its perpetrators (all illegal immigrants to Delaney, poorer "sweaty campesinos" to Candido); both seek safety in the mountains; both find their fears following them.

By the book's last third the polemic has been redirected, from the rich oppressing the poor to the cruel oppressing the decent. Delaney becomes more sympathetic, his whines and self-deceptions seeming human beside the career obsessions of his wife, who finds spiritual fulfilment in a saleable property, and his increasingly vigilante neighbours, who are roused by a convicted fraudster to build a thick wall around their development, obscuring all view of the outside world.

This shift does not quite work. The bad guys are now so vaguely defined - bad because they're just, well, bad - that the previous insights into California and America disappear in a haze of liberal sentiment (Boyle's not Delaney's). So many social and political contradictions - such as Candido's gleeful acceptance of work building the wall that will exclude him from the development - have already been revealed by the author's sharp eye that this kind of conclusion may be unavoidable. But it dissipates the anger of the opening, and Boyle - whose lyricism never becomes sufficient in itself, as Richard Ford's does - reaches for a cartoonish climax. The Tortilla Curtain ends with two contrived natural disasters, its dramatic panorama ultimately shrinking, after a long and at times thrilling view, to the width of a scene from a disaster movie. Boyle has not written his great novel yet.