Depravity in Dreamland : L.A. CONFIDENTIAL <i> by James Ellroy (Mysterious Press: $19.95; 512 pp.) </i>

Almost everybody in “L.A. Confidential� dies. Those who don’t wish they had.

In the incontinent mayhem that masquerades as a James Ellroy novel, the line between the quick and the dead is fine. Only the ungrateful deceased are permitted to rest--in pieces, most likely; in hell for sure. For the living, it’s just a question of time.

Dead or alive, nobody is clean. Sasquatch-sized skeletons spook every closet:

Edmund Exley--protagonist only by virtue of longevity--is a Los Angeles Police Department comer. He is billed as a war hero. Actually, what he had done in the war, Daddy, was to artfully arrange a row of Japanese corpses, fry away the evidence with a flame-thrower, and accept the Distinguished Service Cross with understandable modesty.

Preston Exley, the father for whose approval Ed lusts, has retired, with laurels, from the force. He is now L.A.’s prime contractor, the man who built Dream-a-Dreamland (read Disneyland) and most of the freeways. Preston did not earn his stake by putting bad people in the pokey.

Ray Dieterling (read Walt Disney), animated-cartoon pioneer and Dreamland godfather, has corrupted one son and murdered another, whose name is immortalized in a Dreamland ride.

Jack (Trashcan) Vincennes, also LAPD, is called the “celebrity crimestopper,� a scabrous sobriquet earned from paid and publicized drug busts of the likes of Robert Mitchum and Charlie (Yardbird) Parker (whom Vincennes frames, then stuffs into a garbage bin; hence Trashcan ). He also has terminated two innocents while he was high on drugs.

Bud White--LAPD, what else?--is a time bomb in blue, ever since his father cuffed him to a bed, made him watch while Dad beat Mom to death with a tire iron, left them both to rot for a week. Bud is somewhat short-tempered with woman-beaters, notably with a gentleman from Eagle Rock whose arm Bud jams into a churning garbage disposal.

Even the fringe felons are given a certain panache by Ellroy--bass player Burt Perkins is affectionately known as “Deuce� for his “two-spot on a chain gang: unnatural acts against dogs�--while the real-life extras in the ‘50s-vintage novel have distinctive personalities of their own: Johnny Stompanato, who, in fact and fiction, is knifed to death by Lana Turner’s daughter; mobster Mickey Cohen, safe in the pen, who has the only good lines in the book (“I have never killed no man that did not deserve killing by the standards of our way of life�).

The plot, faster than a stray bullet and equally random, ricochets about two police cases--one past, one present, each bearing on the other.

The earlier crime--the “solving� of which earned Preston Exley his wings--is a surpassingly grisly attempt by two maniacs to surgically assemble a “perfect� human being from the body parts of slain children.

The more recent abomination is a shotgun massacre at the Nite Owl Coffee Shop. Ed Exley draws this assignment.

Under pressure from Chief William Parker (the same), Exley corrals three black men, who happen to have perfect alibis: At the time Nite Owl was going down, they were gang-raping a kidnaped Latina and “selling her out� to their friends. Unimpressed, young Exley butchers all three--who are, incidentally, unarmed--and earns yet another promotion.

Among other depravities linking the two cases is a porn ring that features--hang in there--mother-son incest on roller skates!

Obviously, Ellroy spares no sensibilities. By Page 25 of a long and chaotic tale, he has offended every color, creed or kink known to man. With equal disdain, he eschews verbs, nouns, adjectives as obstacles to his unique narrative flow. What is lost in clarity is recouped in concision: One Ellroy paragraph is tantamount to a page, even a chapter in more measured parables. To wit:

“Bud packed up, got out, brainstormed some more--pimp war clicks, clickouts--Duke Cathcart had two skags in his stable, no stomach for pushing a 14-year-old nymphet--he was a pimp disaster area. He tried to click Duke’s pad tossed to the Nite Owl--no gears meshed, odds on the (blacks) remained high. If the tossing played, tie it to Cathcart’s ‘new’ gig--Feather Royko talked it up--she came off clean as Sinful Cindy came off hinky. . . .�

Got that? If you have, and if Ellroy hasn’t yet driven you to droolsville, you’ll doubtless identify with one Timmy Valburn, the man under Dreamland’s “Moochie Mouse� suit:

“Jack,� says Timmy during interrogation, “I’m tres Hollywood. I dress up as a rodent to entertain children. Nothing surprises me.�