The novelist's role is to remember. John Gregory Dunne pauses, determined to get it right . . .

He is the chronicler, in "True Confessions," of the Spellacy brothers--detective Tom and Monsignor Des. In postwar Los Angeles, a young woman has been cut in half, the cops are corrupt, the church is a political machine, the mosty venal parishioner is named Catholic Layman of the Year, Detective Tom ruins Monsignor Des and the monsignor thanks him for it.

He is the chronicler, currently, of the present-day Irish-American lawyer protagonist of "Dutch Shea, Jr." Dutch skillfully represents pimps while morosely inhabiting a world of courthouses, morgues, death, rot and scum. His daughter's head is blown off as the book begins, his father has hanged himself in jail, his wife has cuckolded him and his mistress is a judge with a pistol on her hip.

Dutch Shea, Jr. has anesthetized himself. His sleazy life, he says, is "chemotherapy for a metastasizing memory."

But John Gregory Dunne, the novelist, remembers . . .

"Joe Alsop, Lillian Hellman, Carl Bernstein, Susan Sontag, Diana Phipps, Bill Styron, me, Jackie Onassis, Peter Jay." It is the seating plan, clockwise, at his table at a memorable meeting of the high literati in New York five years ago. Memorable among other reasons because Gore and Norman, Vidal and Mailer, had a fight. "Every table was like that, just wall-to-wall celebrities."

That's John Gregory Dunne's milieu. But not Dutch Shea's. You couldn't get Dutch in there in handcuffs. They wouldn't let Dutch in there in handcuffs. When John Gregory Dunne, the novelist, is remembering, how does he come to remember Dutch Shea, Jr.?

Dunne is married to Joan Didion. They are double-barreled heavy armament of the New York-Los Angeles literary-industrial complex. Their books sell hundreds of thousands of copies, they appear in The New York Review of Books and they are simultaneously the best-known husband-and-wife screenwriting team in the country: "Play It As It Lays," based on her novel; "Panic in Needle Park"; "A Star Is Born" (from which they withdrew); "True Confessions," based on his novel. Their next script is of his first novel of 1974, "Vegas: Memoir of a Dark Season." They dine at Ma Maison, a Los Angeles restaurant that serves Orson Welles three times a week and maintains an unpublished telephone number.

Dunne is 49, with the manner of a journalism aristocrat. The names of famous friends flash in his conversation like neon sculptures at a celebrity gallery opening.

Dutch Shea, Jr. knows only the dregs of society. The stuff thrown into the melting pot that won't melt. Arsonists and untouchable pimps and sociopaths.

John Gregory Dunne goes to the movies a lot, because he has an excellent neighborhood theater. "We call it 'Loew's Lear.' That's because it's the private screening room in Norman Lear's house, only a few blocks away. Norman runs a double feature every Sunday night," Dunne explains. "Gore is a regular." As in Vidal. "Yes, you're allowed to talk during the movie, especially if it's not much good. Sometimes Mel and Carl Brooks and Reiner break into their "2,000-year-old man" routine. That's pretty tough competition for any movie."

He and Joan are in Hawaii at the moment. They have been vacationing there for years. They are quite rich. He drives a Jaguar. After Hawaii they are going to El Salvador.

Dutch Shea, meanwhile, lives in a crummy apartment, killing time and his soul:

"Reasons to attend Mass: (1) It took up an hour. Counting 10 minutes to drive to church and 10 minutes to drive home, an hour and 20 minutes. Throw in 10 minutes in the parking lot. Hiya Jack, Hello, Charlie. Plus breakfast at the Pancake House. Another 30 minutes. Two hours in all. Mass was like taking another Legal Aid case. Religion as anesthesia. Ditto the law. Ways to anesthetize memory. (2). See 1." Reconstructing a literary party on demand five years later: John Gregory Dunne enjoys that sort of thing? A shrug. "Joan and I never go out two nights in a row." In Washington, he dined at Nora's, and said he knew 40 of the patrons. "It's nice to know somebody in another city. Beats eating dinner alone, like I had to in Chicago." In the Palm at lunch he recognizes eight people. A social eye. A novelist's eye. To know what people are like, you have to remember to look.

In "Dutch Shea, Jr." nobody is chic or has been to Hawaii, much less El Salvador. The best they can hope for is final absolution. An answer in Latin to a plea in Latin: mea culpa, mea culpa, mea maxima culpa.

Where did Dutch Shea come from? Certainly not from John Gregory Dunne's observable life, which is an open book--specifically, page 111 of "Current Biography": "Socially the Dunnes see many members of the Hollywood film and television colony, including Warren Beatty, Jack Nicholson, Jane Fonda, Robert Towne, Norman Lear, and assorted screenwriters, studio heads and record company executives."

Page 111 fails to mention Calvin Trillin ("my oldest and closest friend") and John McPhee ("he was a year ahead of me at college; I've known him for 100 years"), who write for The New Yorker, not the movies, but who are often credited nowadays with the invention not only of Non-Fiction Prose but of the Indo-European Language Group itself. Dunne calls Trillin "Calvin," which is one up on his nickname "Bud"; McPhee calls Dunne "Greg," Dunne reports, because "in college that was what they called me."

Dutch Shea, Jr. has well-known pals, too. Beaubois, Robert N.M.I., accused of arson. The N.M.I. stands for No Middle Initial. Peekaboo Cagney, a private investigator. Myron Mandell, an arrogant pimp. Biographies written in police-form English: "Susp. was calm and cool at first and then susp. became extremely agitated in an agitated manner."

Dining on steak at the Palm, susp. Dunne was calm and cool at first as he revealed why and how a well-connected upper-middle-class observer living in Los Angeles writes about doomed Catholics in a world of sleaze. Then susp. became extremely more calm and cool in a calm and cool manner, right down to his penny loafers.

Dutch Shea, Jr. certainly must be curious. Dunne created him, but the child is father of the man. Go ahead, Dutch, put him through the paces. Cross Examination By Mr. Shea:

Q: You are of Irish-American descent, Mr. Dunne, is that correct?

A: My grandfather arrived in 1861. He opened a grocery in Hartford, Conn.

Q: Was he poor?

A: He also opened a bank. He was very rich.

Q: Was your father a policeman, priest or politician?

A: He was a doctor. He went to Harvard Medical School.

Q: Your brothers, then, went into the 'Three Ps'?

A: My brothers went into Williams, Yale and Harvard.

Q: And yet you chronicle a tortured Irish-Catholic sensibility?

A: I've got the face, I've got the name.

Q: And you call them 'micks'?

A: I'm an upper-middle-class 'mick' myself.

Q: Are you are a Catholic, Mr. Dunne?

OBJECTION: Your honor, Mr. Dunne's church-going habits are not at issue here.

MR. SHEA: Your honor, this is a book about despair written by a man who is personal friends with Warren Beatty. I'm trying to . . .

EXAMINER: Be careful, Mr. Shea. Go ahead.

Q: Do you have a religious affiliation, Mr. Dunne?

A: I'm an avowed Catholic. I'm not a practicing Catholic.

Q: And what college was it your father went to?

OBJECTION: Asked and answered.

EXAMINER: If you have a point, Mr. Shea, come to it.

Q: When you were at, ah, Princeton, Mr. Dunne, did your classmates ask you where your father had gone to college?

A: Yes.

Q: And what did you tell them?

A: Harvard.

Q: Harvard Medical School?

A: No, just Harvard.

Q: Were they asking where your father went to medical school?

A: No.

Q: Were they asking where your father went to college?

A: Yes.

Q: And you told them?

A: No . . . to my shame.

Q: So now, Mr. Dunne, many years later, let me ask you the same question. Where did your father go to college?

A: . . .

EXAMINER: The witness will speak up, please.

A: Catholic University.

Mr. Shea: I have nothing further. Courtrooms & Catholicism --

Dunne says he was in his early thirties when he realized the significance of saying "Harvard" when he should have said "Catholic U."

"Yes, I said it. As I say, to my shame, but I said it. It's funny, because we were always Catholics. But we were assimilated. We didn't think about it. I mean, my sister was the first Catholic girl in the Junior League. It was in the 1960s that I became aware of what had happened. It wasn't until I was writing 'Vegas' that I realized my Irish-Catholic background could be a fertile field."

The farming will continue. His next book, now in notes form, has as its working title "The Red, White and Blue." It's the story of an Irish-American family over several generations. "They're still Catholics, sure. They just don't make a meal of it."

If Dunne's conversion on the road to "Vegas" explains his subject matter, his life style tends to be a little short of morgues and such. To remedy that, there is research. He and Didion are known as inveterate visitors to courtrooms at home and abroad.

"We made a trip to Malaysia, and went right to the courthouse in Kuala Lumpur. The lawyers and judges were Chinese, and they wore little white periwigs. They spoke this plummy, Oxfordian English to each other, and then they went and explained to their clients in Chinese."

As for just how a bullet should penetrate the medulla oblongata, Dunne got that tidbit from Soldier of Fortune magazine, as he gleans others from the American Lawyer and Police Magazine. For Irish names, he subscribes to Chicago Irish-American. For Jewish names, "any of those newspaper ads with the list of patrons down the side."

As for morgues, he and Didion made a visit to the one in Los Angeles at 2 a.m. "Here are all these bodies stacked around, wrapped up in brown paper. The cop who's showing us says, 'Here's an interesting one,' grabs the paper and rips it down the middle. He doesn't unwrap it, he rips it with a big tearing noise. Then we go into the autopsy room, and there's seven tables, with seven staffers cutting away. Bottles of organs on the shelves. But what you're conscious of first is the noise. There's a tremendous loud noise from the power saws they're using to cut open the craniums."

As for the scabrous jokes that pepper "Dutch Shea, Jr.," his ear is loyal and his taste at best eclectic. One in particular had this origin:

"We were at a press preview for the movie of 'True Confessions' in Boston, stuck in the snow in a car, and Bobby DeNiro's agent told it and everybody laughed like crazy. The first thing I did Monday morning was put it in the book."

As for the accouterments of Dutch's world, a world of Preparation H, K-Y jelly, Kaopectate, Hydro-Diuril, Ortho-Gynol, cellulite and crusty linen, they are only mundane; like the hebes, ginneys and dinges randomly defamed in Dunne's narrative, they have meaning only as perimeter markers for Dutch Shea's despair. Within that same unenchanted circle, however, is the Church. God may have died on the cover of Time magazine, but novelists are not so willing to give Him up. In Dutch's crummy world, He alone provides at least the specter of final absolution, after one last heartfelt act of contrition. "Sure, most Catholics accept that," Dunne says. "There's always that last chance."

But "Brideshead," the BBC rendering of Evelyn Waugh's saga of Catholics and real estate, he found a "sumptuous bore."

"Did you see Lord Marchmain there at the end?" Dunne marveled, imitating a feeble codger hesitantly making the sign of the cross. Charles Ryder struck him as "a bore and a prig, really a terrible character in book and film. I was talking to Diana Quick, who played Julia, when she was just about to go off to film the boat sequences on the QE II. I told her Ryder is a vile character, a stick.

"She said she agreed with me." The Stuff of Memory ------

Novels have a way of chasing their authors down, of guiding them with an unseen and sometimes heavy hand toward long-buried but inevitable themes. Dunne puzzles over this himself. "You start out to write a story, but however you change it it's going to be about memory."

Sometimes the memories are fresh. Suicide was a technical device of various potential applications in "Dutch Shea, Jr." until, during the writing of the book, his brother Steven killed himself. "It was only a plot point until then," Dunne says. Such subjects are what books are for.

For Los Angeles, he has a Jaguar and famous friends. When he goes out with either, it is on the fast track.

But Dunne never goes out two nights in a row.

One night to live, the next to remember.