Geraldine Brooks has never written an entirely fictional book. She does not even think she could. She spent too many of her writing years, she says, “in service of the facts,” practicing journalism.

In a way she still does practice journalism, for her novels are born of news judgment rather than imagination. The initial inspiration for every book is invariably a true story, and a particular sort of story, in which only a few compelling facts are known, but the detail is missing.

“I like to find these stories where you can know something but you can’t know everything,” she said over a recent lunch at the Black Dog in Vineyard Haven, the town where she also now makes her permanent home.

Enough detail to fire the imagination, but not enough to direct it, or get in the way of her invention.

Her third novel, People of the Book, due out in January, spins off such a story. It traces the history of a book, an illuminated 15th century Hebrew codex, from its creation during the Spanish convivencia when Jews, Christians and Muslims coexisted peacefully, through to its modern day rediscovery in war-wrecked Sarajevo.

The book in People of the Book is a real one, the Sarajevo Haggadah. It really did disappear when the libraries and museums of Sarajevo were under shell fire and burning. And the Jewish text really was saved by a heroic Muslim librarian.

Ms. Brooks first heard of it while she was reporting the tragedy of the Bosnian war for the Wall Street Journal.

She overheard some other journalists speculating about its fate. Had it been burned? Had it been smuggled out by Israeli agents?

Jaxon White

“They had all kinds of wild ideas,” she said.

“I remember at the time thinking, how interesting, this book was created at a time when everyone was getting on in Spain in the convivencia period when Muslims and Christians and Jews were all working together.

“It was peaceful and creatively rich and everybody was influenced by everyone else. Then boom-de-boom up comes this hatred and fear of the other. Somehow the book survived that to wind up, six centuries later in another place where exactly the same story was unfolding.

“That was the first point of fascination, then after I got to know a little bit more about the other things we didn’t know, I thought, this is perfect man. Lots of voids, but a good scaffolding.”

And so she set about filling the holes in history.

“A pothole filler, that’s me,” is her self-deprecating way of describing her literary niche.

“It’s not like I set out to be a novelist. I was very happy being a journalist. I loved that life.”

But when she got pregnant she knew she had to stop being a foreign correspondent.

“That kind of journalism — going on long, open-ended assignments to pretty dicey places — didn’t seem compatible with having an infant,” she said.

So she turned to book writing. Her first, Nine Parts of Desire, the secret lives of Islamic Women, was nonfiction. Her second, Foreign Correspondence, filled some of the holes in her personal history, tracing the lives of her childhood pen pals. Part memoire of her Australian childhood, part travel adventure it was, she says now, “a weird book, a transition book.”

It won her an award for Australian women writers, and with that came $20,000.

“I wanted to use it to buy some time with this idea that had crossed my radar ten years earlier,” she said.

She used the money to fund her first effort at a novel, based on a story she happened across years earlier, through journalism.

“I was back from the Middle East for a rare weekend,” she recalled. “Tony [her husband Tony Horwitz, who is a Pulitzer prize winner, like herself] had to go to do a story on militant ramblers . . . which is one of my favorite oxymorons.

“They were doing a mass trespass in the Penines, so we were covering that and decided to explore a little bit afterwards and saw a sign saying Plague Village.”

It was the village of Eyam, where, in 1665, there was an outbreak of bubonic plague. Instead of fleeing and spreading the disease as so many others did, the people of the village quarantined themselves. Over 16 months, three-quarters of them died.

“The story hung with me,” she said. “It was just so moving, trying to imagine what it would be like to bring a community to a decision like that and live with its consequences.”

“So I typed out a few chapters of a draft and sent it to my nonfiction agent and said, ‘Be blunt, be cruel, I can go back to my day job and find another nonfiction idea.’

“I didn’t hear from her for a long time and thought ‘Oh, it was garbage.’ But she had taken the chapters and shopped them around and the next thing I heard, she’d sold them. Then I had to write it.”

The book was enthusiastically received.

Her second novel, March, which won a Pulitzer last year, “came out of arguing with Tony about whether we were going to waste another beautiful weekend schlepping around Civil War battle fields — and losing that fight and getting interested gradually in the dilemmas of conscience of the common soldier.”

She based the central character on a real man, Bronson Alcott, who was the father of the famous children’s novelist, a serious thinker of his day and a major influence on Emerson and Thoreau. But he was largely written out of history, much like the father was left out of Little Women.

Ms. Brooks filled in the historical blanks and came up with a superb novel about idealists at war, centered on the character she calls “that famous but little-known idealist Mr. March.”

“That one just flew in, gift-wrapped,” she said.

But not every idea goes so well. Like the story she started about Jane Franklin, wife of the Tasmanian governor during the 1830s. Franklin was an adventurer who explored the southwest wilderness of Tasmania and a political radical who agitated against the treatment of Aborigines and woman convicts

“Her husband got summoned home in disgrace for doing a bad job in Tasmania, and a lot of that had to do with her getting in the faces of the establishment people,” said Ms. Brooks.

The problem was Mrs. Franklin was a meticulous diarist.

“If you’ve got a journal that someone wrote every day, down to the penny she spent, it doesn’t leave a lot of room for imagination.

“She didn’t leave me enough room so that one didn’t work.

For a long while, it seemed like People of the Book was not going to work either, although for a different reason. Ms. Brooks could not get the voice of the central character, a woman conservator called in to examine the book in Sarajevo.

“But I just couldn’t get her voice right, because Bosnian Serbs, Sarajevans particularly, have a unique voice. It’s something to do with this mordant wit, something to do with a Slavic soulfulness, overlaid with this ability to absorb and endure suffering. It all comes together in this kind of delicious Balkan stew and I just wasn’t getting it. She wasn’t very convincing.”

She binned 50 pages. She put the idea away in a drawer for a year and wrote March.

When she came back to the project, Ms. Brooks tried a new voice central character — whose examination of the treasure yields the little clues that open episodes in its history — that of a contemporary Australian woman.

“That was a voice I could hear. I didn’t have to go to a library for that one. And there she was in all her enjoyable crustiness, and I just started to like her so much that she took over the book,” Ms. Brooks said.

Two things worried her a bit. The first was that people would think Hannah Heath was her.

“And she’s not based on my life experience. No, no, no, no, no.

“She’s got a terrible relationship with her mother. I haven’t. She’s very emotionally damaged and I hope I’m not. She’s a bit of a chicken; I hope I’m not. She is kind of sexually reckless and . . . perhaps we shouldn’t go there,” she laughed.

“She’s not in any way me, but she’s a voice I knew because she’s a voice I grew up with.

“And I gave her some tastes of mine. Everything from her love of the prawn sambal at the Malayan restaurant to her getting lost in the writing process and stuff like that.”

The second worry was that readers wouldn’t buy the premise that somebody had been dragged all the way from Sydney to do work on this European treasure.

“At that point I was really interested in how real conservation scientists research a stain on a parchment, so I had e-mailed the chief conservation scientists at the Fogg Museum at Harvard.

“He e-mailed back saying ‘Sure, come and we’ll splash some wine on some parchment and I’ll show you how I would analyze it.’

“And when I get there he goes, ‘Gedday mate.’ The chief conservation scientist at Harvard is an Aussie bloke. That made me feel much better,” she laughed.

Ms. Brooks has twinkling eyes and a ready laugh. She thinks of herself as a sunny, optimistic person.

Why, then, are her books so steeped in tragedy and suffering?

“I don’t know. I’ve obviously got a little inner Stephen King that I’m trying to feed.” The musical laugh surfaces again. “But seriously, I think if you’re going to write about the Spanish inquisition, you’d better get into it and do justice to the suffering.

“People in catastrophe, I keep coming back to that. How are you in a catastrophe? Does it lead you towards your best self or your worst self?”

Well, so far she’s done the Black Death, the Civil War and the Spanish inquisition. Next catastrophe?

“Something very close to home,” she said.

She means a story set here, in her adopted home on the Vineyard. She does not want to say too much yet, in case the idea falls over, but she’s looking at the effects of early white culture on the Wampanoag Indians.

She needs to find the voice. And she needs to do more research.

But given this Island’s obsession with its own extraordinary history, she can be pretty confident of finding what she needs to get her imagination going.

“I hear rumors,” she said, sparkling at the thought, “of boxes and boxes of uncataloged material . . .”