LONDON – Edna O'Brien is going home to Ireland, and she hasn't even begun to pack yet.

"I'm very sorry," says the novelist, apologizing for the lateness of the hour, as she heads for the upstairs parlor of her South Kensington home. It is from this quiet, book-lined room that she has viewed her Ireland, her County Clare. Fifteen novels, half a dozen plays and numerous short stories have poured forth – all of them about her home country – establishing her as one of Ireland's greatest living writers.

She is heading to Ireland to mark the release of her 18th work of fiction, The Light of Evening, a novel about a famous writer coming home to Ireland to her dying mother. It is symbolically loaded territory for Ms. O'Brien, which explains the extra nervousness about the trip.

"My mother hated, went to her grave, shocked, outraged, that I was a writer," Ms. O'Brien says, seated now, her huge, expressive eyes clouding with emotion. "She saw that I had some gifts. She resented it and yet wanted us to be bound together. And that's very unnerving."

Rather than bury this tension, Ms. O'Brien has given her mother her wish. In The Light of Evening she has taken the letters her late mother wrote to her during the course of her life and spliced them almost verbatim into a fictional story, mother and daughter bound together indeed.

"The letters were little masterpieces of her own life in her own existence," Ms. O'Brien explains, "and they captured everything: all the little strangleholds she placed on myself. They had to see the light of day."

In the novel, 78-year-old Dilly goes to the hospital, where she learns she has ovarian cancer. While nurses attend to her, Dilly awaits the return of her famous writer daughter, Eleanora. Dilly passes the time reminiscing on her own journey away from Ireland and to America in the '20s, recalling the guilt-inducing letters her own mother wrote to her.

The book then jumps back to Eleanora's grown-up life in London, where she is lonely and homesick.

At every step of the way there are letters from mother to daughter. The book ends with a powerful stream of them. They are loving, yearning, accusatory. "I wouldn't want you to deny your mother like Peter who denied Christ," Dilly writes in one dagger of guilt.

Ms. O'Brien says she was understandably "quite jittery" when she received letters like this from her mother. Like the fictional Eleanora, Ms. O'Brien was born in a small, rural Catholic village in the west of Ireland, the population just 200. She escaped this provincial life by attending pharmaceutical college in Dublin, then eloping to London with her husband, the Czech writer Ernest Gebler. She never moved back.

But her life has hardly "been a romp," as she says. She divorced Mr. Gebler in 1964 and raised her two children alone. In 1966, when she published her first book, The Country Girls, it was banned, then publicly burned by her parish priest back home in Ireland.

Her mother went through the tale, about two girls trying to escape the strictures of their convent life, and inked out any offending words.

"She hated the written word," Ms. O'Brien says. "The line in the book 'Paper never refused ink' was one of her more caustic lines about my writing."

For all the points of contact between this book and her life, though, Ms. O'Brien, 75, insists this is not a veiled autobiography. "This is a version of my life, an imaginary version of it," she says. "I don't know anything about my mother's life in Brooklyn; all I know is she worked in America as a maid and came home and married somebody in Ireland."

Nor is it a settling of scores. "My mother was an amazing, powerful woman," Ms. O'Brien says, "but she was also lost."

In order to fill in the gaps in her story, she traveled to New York and visited Ellis Island. "I walked up and down streets in Brooklyn, I took that ferry out to the Statue of Liberty over and over again," she says, "and then I just got so despairing. I thought, 'I don't know this world! I don't know it!' "

She was relieved when the Irish-American memoirist Frank McCourt read the manuscript and told her she had got it right. "That meant a lot to me."

Like Mr. McCourt, Ms. O'Brien has a complicated relationship with Ireland. She loves the country, but it has not always loved her back so forcefully.

Her first six books were banned, and critics often treated her later books with "excessive contempt," she says.

She pauses to show the James Joyce medal she finally recently received. "There, put that piece of metal around your neck," she says, joking, before indicating that the medal had indeed meant something to her.

Asked whether she thinks her reputation has suffered because she is a woman, she does not pause before answering, "Absolutely. The hard part about being a writer in the big wide world is being a woman, too, because they don't want or expect a woman writer to be in the same league."

But this has not stopped Ms. O'Brien, the books coming at such regular intervals that she has begun to be regarded as something of a force of nature. Bad reviews still hurt, and good ones cheer, but "I will have the last word," she says with a laugh. Much of her time is spent in this room, her study, where she works in longhand, a typist stopping by when composition has ceased.

She lives so fully in the life of her mind that as the light falls, she begins to trip down a path of associations and, midconversation, quotes at length from Joyce or Faulkner.

In the past few decades, these two writers have been her adopted ancestors, her imaginary countrymen. The venerable Yale professor and critic Harold Bloom wrote her a letter after reading The Light of Evening. "Joyce I think is your mother, in this book," he wrote, "and Joyce influenced Faulkner, your father."

Ms. O'Brien has never been to the South, but she understands the mythological similarities between her fiction and Faulkner's. "In the part of Ireland I come from there are the big houses, the ruined houses, the blood boiling in the land, 'the silence underneath which is simmering so much.' "

Sitting in almost total darkness now, Ms. O'Brien says if there was one book she would have loved to have written herself, it would be As I Lay Dying, Faulkner's novel about the Burden family's trek across Mississippi to bury Addie, wife and mother, in the town of her choice. "It's a wonderful book, I love it," she says, a reverential hush falling.

With The Light of Evening, she may have just achieved her wish.

John Freeman is president of the National Book Critics Circle.