To Live and Discriminate in L.A. : It’s us versus them, natives versus immigrants, haves versus have-nots : THE TORTILLA CURTAIN, <i> By T. Coraghessan Boyle (Viking: $23.95; 355 pp.)</i>

Los Angeles is so amorphous and ephemeral, novelists can rarely capture its crazy patterns, much less its ‘90s angst. In “The Tortilla Curtain,” T. Coraghessan Boyle--celebrated satirist, former USC writing teacher and Woodland Hills resident now living near Santa Barbara--has done the job to a fare-thee-well. The problem is that while the writing and pattern-making astonish, the book is cold and its message is “Abandon Hope, All Ye Who Enter Here.”

Hovering over the book is the question of who’s a Californian (answer: everyone and no one). In “The Tortilla Curtain,” everybody comes to Los Angeles from somewhere else, and the claims they make on its bounty vary with their needs and their hubris. Boyle portrays the sociobiological stress of diverse and competing populations so compellingly--cars “racing bumper to bumper up the canyon like a snaking malignant train”--that readers who have been feeling anxious in L.A. may find themselves packing their bags after reading this book.

The title refers to a security fence that some propose building between the United States and Mexico to stem illegal immigration. This is a book that bigots can love; it drips with racism and xenophobia. If you’re white and angry, reading this book may be a guilty pleasure with its lustily incorrect expressions of white backlash. If you’re Latino, it’s probably hard not to take it as an insult (which the author’s conspicuous dedication to a Latino-surnamed couple only serves to underscore, not soften).

Like Tom Wolfe’s “The Bonfire of the Vanities,” the book kicks off when people from two very different socioeconomic strata meet by vehicular accident--sensitive white nature writer Delaney Mossbacher (shades of Georgette) and homeless Mexican illegal immigrant Candido Rincon (shades of Candide). Delaney hits Candido with his precious Acura and gives him a 20 to get lost. When Delaney (“he did feel that he stood apart from his fellow men and women, that he saw more deeply and felt more passionately--particularly about nature”) realizes that Candido has been camping in Topanga Canyon, that bastion of L.A. live-and-let-livism where he resides, he feels his “guilt turn to anger, to outrage.”

Delaney is married to Kyra, a luxury-obsessed and obtuse real estate agent with “pale blond hair and see-through eyes.” They live with her Nintendo-playing young son in a luxury Spanish mission-style home in a planned tract called Arroyo Blanco, a Stepford-like development where non-whites need not apply.

The Mossbachers’ neighbors propose building an impenetrable fence around Arroyo Blanco, ostensibly to keep out snakes and coyotes, but actually to keep out criminals and trespassers like Candido and his young pregnant wife, America, who live desperately by a stream bed. While the Mossbachers gorge themselves on various health and ethnic cuisines, the Rincons taste the most modest of foods with a pleasure the Mossbachers’ jaded palates will never provide. The Rincons are God-believing sensualists; the Mossbachers, agnostic consumers. Kyra makes love only when she’s upset, and in one funny scene she loses the mood upon learning that a coyote has carried off one of her precious little dogs.

For Candido and America, there is no work too toxic or degrading. He makes money helping to build the fence meant to keep him out, and she risks poisoning her baby to clean statues of Buddha for a fat and opportunistic local gringo. And yet, as trouble continually befalls the couple--America is raped in a graphic passage, Candido loses their money stash not once but twice--they begin to appear ridiculous. Candido is “a failure, a fool, a hick,” he thinks to himself. At the book’s end, Boyle tries to tie his stories together by having Candido reach out to save Delaney during an earthquake. (Here, you remember themes from junior high school English: man against man, man against nature.) It’s a falsely humane note. Candido is the buffoon, the downtrodden, cliched Mexican who can only accept his fate.

Boyle’s last satire, “The Road to Wellville,” was made into a bad bathroom-joke movie. You can’t help but think that he wrote “The Tortilla Curtain” with Hollywood at least partly in mind--the dual story line and the cartoonish characters could easily translate into 90 minutes of distraction. But as a novel, it seems curiously cold-blooded. If Boyle wrote out of anger, he has failed to convey it.

On the back of the review copy of “The Tortilla Curtain,” the blurb calls it “a ‘Grapes of Wrath’ for the ‘90s.” Puh-leeze . Although Boyle may not be responsible for that unearned accolade, there inside the book, before the acknowledgments page, is a quote from John Steinbeck’s Nobel Prize winner. It’s puzzling. Published in 1939, “The Grapes of Wrath” stood plainly for workers and decried the concentration of wealth in too few hands. But Boyle takes no position while focusing on immigration, demagoguery’s classic red herring. Why the appropriation of Steinbeck? The grapes of wrath are dearly owned, never borrowed.

“The Tortilla Curtain” is also available (abridged) read by the author on two audiocassettes from Audio Renaissance ($16.95).