It’s a Tougher--but Not Truer--World : BORDERSNAKES by James Crumley; Mysterious Press; $22, 320 pages

A good hard-boiled novel is like a ride at Magic Mountain. It scares you breathless, turns you upside down and inside out and makes you almost forget that your life isn’t really in danger, that there’s no chance your roller-coaster car is going to jump the rails. In short, that it’s just a ride.

James Crumley’s “Bordersnakes” is like that. It burrows into the maggoty underside of American society, introduces us to people we’d run like hell to get away from if we met them anywhere except in the pages of a book, then does its best to persuade us that their vision of life is the true one and our squeamish, insulated existence is a lie.

Milo Milodragovitch and C.W. Sughrue, the Montana private-eye heroes of some of Crumley’s previous books (the last of which, “The Mexican Tree Duck,” won the 1994 Dashiell Hammett Award for Best Literary Crime Novel), team up as our guides to this particular Inferno.

Somebody gut-shot Sughrue, left him to die and, for the first time in his alienated and violent life, actually frightened him. He’s hiding out in a trailer in the West Texas desert with his wife and stepson, dressing like an Apache, stockpiling food and guns and reading Dickens’ “Hard Times” to the kid because it’s truer and tougher than any Dr. Seuss book could hope to be.

Meanwhile, a pipsqueak banker and a butch lady poet stole Milo’s $3-million inheritance and disappeared. Though Milo is older--he fought in Korea, Sughrue in Vietnam--and a tad more sensible, he, too, hankers for revenge. He sets out in a spiffy Italian suit and a red Cadillac he nicknames “the Beast,” following the thieves’ trail south to an area along the Mexican border inhabited by “three kinds of drug smugglers, six different breeds of law dogs, and every kind of criminal ever dreamed up.”

In a word: bordersnakes.

For no very plausible reason, the bad guys who victimized Milo and Sughrue are connected. A bizarre crew they are, too: barroom brawlers, steroid freaks, Hollywood wannabes, Mexican cocaine lords, a retired U.S. general with Iran-Contra in his resume. The good guys pursue them through blood-spattered locales all over the West, including a house in Austin, Texas, where a couple were tortured to death and a patch of wasteland where Milo is forced to dig his own grave.

Of course, “good guys” is a relative term. A scuzzier pair of hard-drinking, dope-smoking, trash-talking testosterone-overdose cases than Sughrue and Milo would be hard to imagine. But they are sensitive to the beauties of music and scenery, capable of friendship and bent double under the burdens of guilt and sorrow, which, as Sughrue explains, is a virtue:

“Sometimes people you love [bleeping] die. You’re supposed to feel bad. For [bleeping] ever. And that is a gift. Most [bad guys], even if you . . . shoot them, can’t even manage to feel bad about their own deaths long enough to stop being [bad guys] that was sad. Feeling bad about the deaths of people you loved: that was hard, but not sad.”

Milo gets frightened as badly as Sughrue, falls off the wagon and abandons what his partner considers to be a hopelessly idealistic aversion to killing people. But he stumbles on the clue he needs to solve the case because, finding a wounded dog in the slain couple’s house, he’s decent enough to take it to the nearest veterinarian.

Crumley’s message is that America has grown so violent and corrupt that good people and the good parts of people are being “hunted nearly to extinction.” A primary cause of this, he implies, is the war on drugs, as hopeless and brutal and wrongheaded as the Vietnam War.

Crumley is unquestionably a skillful writer. “Bordersnakes” is salty and funny and, at times, unexpectedly lyrical. The characters (including some women as dangerous as any of the men) are vividly drawn. But unlike the few hard-boiled novelists, such as James Ellroy, who actually do subvert our sense of reality and thus are genuinely scary, Crumley is working with a net: a basically romantic view of things, a twisted but recognizable version of the Code of the West.

Sughrue and Milo, we soon realize, are immortals. They can be beaten up, stabbed, shot, but never killed. Nor can they ever quite lose their integrity. It’s to hide these limitations that Crumley lets his plot metastasize and piles on so much violence that it begins to lose its impact. The world he shows us is tougher than ours, all right, but in the end we can no longer agree that it’s truer. As entertaining as “Bordersnakes” is, it’s just a ride.