She looks frazzled, just back from a whirlwind tour of the booksellers, in her wrinkled white linen jacket and plain black cotton skirt and damp, honey-colored corkscrew curls. Frazzled and out of place, as if her parachute had opened at the last minute, depositing Sue Miller -- America's bestselling unknown author -- on this expensive, glassed-in chunk of Manhattan terrain without an interpreter.

She is smart. And serious. Not given to small talk or fast talk or the tube talk of a glossy-lipped author trying to sell herself. She doesn't have to. She has just seen her first published novel, "The Good Mother" (Harper & Row), land on The New York Times fiction best-seller list (by its third week, it was No. 4, right behind megabooksters John le Carre', Judith Krantz and Robert Ludlum). On this very day, she is waiting to learn who will win the hot bidding war for the paperback rights. At 7:30 p.m., the word comes down. It's Dell and they're paying just under $1 million.

A major studio has optioned the book for a film. Jessica Lange is "in-terested," Miller says with a trace of awe.

If the screen version of "The Good Mother" even comes close to capturing Miller's wrenching story of divorce, sexual passion and parenting, it should be a smash. The stuff of Oscars. Boffo bucks.

But Sue Miller, a single parent for 12 years, a 42-year-old struggling writer from Cambridge, Mass., a woman who was told by one professor that her work would never earn any money, is cringing all the way to the bank. She never thought her book would be a commercial hit, and come to think of it, she's not too sure she likes it.

"It's an utterly alien thing," she says, weighing each word carefully. "I just can't wait till it's over. It's a wonderful thing. I don't mean to bitch about it, but it's not something I can relate to."

She picks at small bits of lint clinging to the black skirt. She is a pretty woman, with freckled skin and the soft, approachable femininity of a good enough mother. "It's been overwhelming for all of us," she says, referring to her second husband (free-lance writer Doug Bauer)sw,-3 sk,3 ld,10 and her 17-year-old son Ben, who has not read the book. "He doesn't read anything I write," Miller says brightly. "I think it's a way of defending himself against it. He doesn't want to know as much about me as might be revealed in the book. I think it's a very good strategy, actually."

She is leaving for Paris in a few days. She and Doug will stay for a month. Writing in the morning and "getting a little shnockered" in some quaint cafe's at night. This kind of freedom, she knows, is what being up there with the Krantz-Ludlum-le Carre' axis can buy. "The idea that I don't have to teach unless I want to is extraordinary. It's also a great responsibility. I feel a little fraudulent at the moment because I'm not working and I'm going around talking to everyone."sw,-2 sk,2

And everyone's talking about her.

The Chicago Tribune called her book "a remarkable accomplishment," "an extraordinarily skillful piece of fiction." Wrote Linda Wolfe in The New York Times: "Every once in a while, a first novelist rockets into the literary atmosphere with a novel so accomplished that it shatters the common assumption that for a writer to have mastery, he or she must serve a long, auspicious apprenticeship. The novel arrives, all its parts gleaming, ticking and we are filled with awe."

Her themes conjure up Tolstoy's, Wolfe continued, and her characters, John Updike's. Pretty heavy stuff for a woman who, up to now, had two unpublished novels yellowing in her drawer and less than a handful of published short stories to her name, which is, indeed, Sue. Not Susan. Not Suzanna. Just plain old Sue.

Miller rejects the notion that she's an instant novelist. "Mine," she says quietly, "has just been a private apprenticeship."

And not all the notices have glowed. The Washington Post found the novel overly didactic; Ms. was irritated by its "passive" heroine.

*But through it all, "The Good Mother," now in its fourth printing, has sold steadily -- 90,000 copies to date. "It seems to have a broad readership," Miller says shyly. "I think it's a good read; it has suspense and tension. I was conscious of working with those elements and wanting it to have a life on that level. But that's fundamentally because I see myself as a reader's writer, not a writer's writer. I see my purpose as being didactic. Talking about how we live and wanting to lecture people on that.

"In order to do that kind of thing you have to write a gripping enough surface so people don't feel lectured at."

The story of Anna Dunlap's divorce from her lawyer husband Brian becomes "gripping enough" when her sexual passion for an artist, Leo, interferes with her role as single parent to her 4-year-old daughter Molly, to whom she is also passionately attached. After an unfortunate misunderstanding, ex-husband Brian accuses Leo of "sexual irregularities" with Molly and a court battle for custody ensues. On the surface, at least, Miller suggests that women must choose between a passionate love affair and the quieter joys of familial love -- the "deep pleasure," as she writes, "in what happens predictably, each day, the healing beauty of everything that is commonplace."

Like Tolstoy's Anna Karenina, Miller's heroine pays dearly for sexual and romantic happiness outside the traditional bonds of marriage. And some critics have expressed dismay that she settles for a conventional life instead of striving toward an I-can-have-it-all denouement.

"I think Anna does settle. But I think most people do," Miller says.

Has the author felt such compromise in her own life?

"I reject that notion from the start," Miller says. "It is true in her case that she can't have it all and doesn't. That's not connected with anything in my personal life. I feel that I simply used this dilemma of hers to write about some other thing."

That other thing, she says, is the pain of loving. Miller -- like Avery Corman, author of "Kramer Versus Kramer" -- hit a bicoastal, baby-boomer tear duct when she chose to write about divorce, child custody and how the courts treat women.

"Those are abstract issues it raises, but those aren't what I see the novel as being fundamentally about," she says. "I think it's about what every serious piece of fiction is about."

Which is?

"How people make use of suffering in their lives and whether there's a point to suffering and how we can understand suffering. What I've done is pick this situation that speaks to a lot of people in order to work with suffering.

"I was lucky," she says, explaining the broad appeal of her subject matter, "in deciding what terrible thing I wanted to do to my character."

As a mother, Anna "gets better and better as the book goes along." In the final analysis, says Miller, she is the good mother, defined by Miller as "one who chooses what's good for the child."

I worried that I was too bound up with her. But then I reminded myself of the feeling I got when I forgot her for 20 minutes or an hour or an afternoon -- the feeling that I was too separate from her. How could I love her without damaging her, I wondered. Not too much, not too little. Is there such a love?

She was born in Chicago, the second of four children. Her father, a minister, taught church history at the University of Chicago, and Miller says she always knew she wanted to become a writer. She attended the now-defunct Faulkner School for Girls ("I was certainly the bright young girl in high school," she says ruefully). She came east to attend Radcliffe in 1960 and didn't do very well in her writing courses.

She married right out of college, had her son and took a "series of peculiar jobs" that included testing rats for the psychology department at Yale, cocktail waitressing and teaching. She won't discuss her first husband except to say he's a psychiatrist. "I don't want to talk about that. I was very young." After her divorce she worked for eight years teaching children in a day-care center.

No, she says, Anna's predicament is not based on any factual case.

"There were a couple of people who had lost custody but not in the particular way it happened in the book. It just intrigued me, that notion. That did seem like the terrible thing I ought to do to that particular character."

During her years in day care, she had become intrigued with children's natural curiosity about sex and how the issue was handled by different parents. "For instance, the kids would be naked in the pool . . . One child would want to touch another's genitals. How do you lay the rules down? What reasons do you give? Those kind of issues seem wonderfully complicated."

Miller says she loved being a single parent in the Cambridge academic community in the early 1970s. "I really felt part of an enormous extended family."

She continued writing, and earned three master's degrees (in teaching English, creative writing and early childhood education). She has taught writing courses at five Massachusetts universities, including Tufts and MIT.

"Should I be doing something now?" she asks the photographer self-consciously.

"You're real stiff now," he says. "What can I do to get you to relax?"

Clearly, this is torture for Sue Miller. She finds comfort in recalling her early writing efforts.

"I think at that time, I was writing in a different way. It didn't please me. I feel I've worked my way around. It seems that I've just written this book and it landed on the best-seller list, but in fact I've written two other novels in earlier stages in my life, neither of which pleased me.

"I at least knew what was wrong. They were simply too thin. Not dense enough. Not rich enough."

So she learned to layer. She read Willa Cather and Christina Stead. "I certainly got enormously better," she says. "But I was really conscious of working to get better.

"I would start with a pared down version," she says, and slowly build it up. "What needs to be looked at? What needs to be smelled? What needs to be described in greater detail?"

The character of Anna made her first appearance in a short story published in 1982 in the North American Review. After two years of carrying around the plot in her head and winning a fellowship from Radcliffe's Bunting Institute (after first being rejected), she started writing "The Good Mother." At the same time, her son chose to board at the school he was attending.

"He was away from me for that year. I think I really sort of implied some of the pain and yearning. I had a terribly difficult time because we had been very close for 12 years, since I'd been divorced . . . really made use of a lot of that feeling that Anna has."

There was no way to retrieve my life with Molly . . . It seemed too full of what would not be. I would not be the name she called in the night or when she was hurt. I would not know the names of school friends, baby sitters. I would miss the odd, funny turns of phrases, the wonderful misunderstandings of the world, I would never have the rocklike comfort of daily life with her. I would be the one she yearned for, as I yearned for her.

She also got a small grant from the Artists Foundation in Massachusetts. "I didn't have to teach a full load. I was teaching three courses. I had run out of dough. It was a terrible time."

She reviewed several law books and "sat in court for a while," trying to master the legalities that would be so crucial to her plot. At the same time, child abuse was becoming a hot topic in national magazines. Miller says the timing was purely coincidental.

In March 1985, Miller's agent took the manuscript to New York. Several publishing houses wanted it, although just as many turned it down. "No one had ever heard of her," says a Harper & Row publicist. Was it a publishing fluke? Did Miller simply have the right story for the right time? The "Love Story" for the '80s? She doesn't want to analyze it. And she doesn't necessarily feel the pressure to repeat it. Having your first novel make the best-seller list, she says, is like making tenure. You don't have to grow old and bitter, envying others their commercial leap. "Now you can do whatever work you have to do. You don't have to think about that anymore."

She is writing a second novel. She is doubtful it will be as big a hit.

"Whatever the coincidences that are making this book do as well as it's doing, I don't think I can tap again."

But for now, her success has given her the opportunity to give up, as she says, "some small chintzy economies." She no longer leaves dirty dishwater in the sink, awaiting the arrival of the next batch of plates. There will be plenty of soap in the future.

"It was delightful," she says, to pull the plug. "To just let go."