After six novels—most of them bestsellers named to end-of-the-year lists by the likes of People, Time, and the Washington Post—J. Courtney Sullivan just might have figured out her writing process.

“I feel like I’m starting to realize a pattern,” she says via Zoom from a small office at her mother-in-law’s house in Des Moines, Iowa, where she’s hiding out, thrilled to be talking books while grandma looks after the kids. “A seed is planted many, many years before the story really comes together.”

Her latest novel, The Cliffs (Knopf, July), which delves into the supernatural and gothic and follows a Harvard archivist whose work and marital troubles lead her to move back home to coastal Maine, took root about a decade ago.

“Every summer of my life I’ve gone to southern Maine,” she says. “That’s where my family always went on vacation when I was a kid. And when I met my husband about 15 years ago, we started going there every summer, too.” It was on one of those trips that Sullivan and one of her best friends came upon an abandoned house she’d never seen before.

“Absolutely beautiful,” she says. “A purple Victorian house overlooking the ocean with all this rolling land down to the cliffs.” The house still had family paintings on the walls, beautiful rugs, books on the shelves, and a doll house inside. “It was not a haunted house, per se, but it’s a house that’s haunted me. For anyone who was ever a lover of Nancy Drew, you know you’re immediately like, ‘What happened here? I need to know everything!’ ”

Sullivan and her friend returned every summer to investigate as the house slid into further decay. “One year, the appliances had just been stolen out of the kitchen,” she recalls. “And one year, the banister had caved in and fallen down.” Eventually, the house was demolished. “It was heartbreaking to me, because although I was never going to be able to afford to buy that house, it had sort of become mine. Once it was gone, I started writing about it. The questions that kept coming up were, ‘Who lived here and why did they leave and where did they go?’ ”

The Cliffs centers on a seaside mansion in Maine, which the novel’s archivist protagonist Jane has coveted since childhood. But when she moves into her late mother’s house and meets Genevieve, the mansion’s new owner, who fears the property may be haunted, Jane is tasked with investigating the manor and the women who have called it home. Lost in old papers and stories, Jane attempts to unravel her history alongside that of the mysterious house.

As Jane delves into the past, Sullivan weaves together elements including spiritualist communities, psychic mediums, and the afterlife with Maine’s history and that of its Indigenous people.

“I feel like a huge part of the reckoning, for all of us, is understanding that American history did not start when the Pilgrims came over and put their boots on the sand,” Sullivan says. “It’s fascinating what’s happening in Maine right now in the fight for tribal sovereignty and the land claims issues that go back to the 1980s. Native people did not go away. They’re still here and they’re still fighting a lot of the same battles that they were fighting 400 years ago. Things are changing, and it’s trickling down to every little museum and historical society.”

Sullivan says she wanted to be a writer from a young age and in third grade started scribbling stories—which she still has in old journals. As an undergrad at Smith College, she studied English literature. “They had one fiction writing class,” she says, “and I took it twice, and then a master class with Kurt Vonnegut.”

Sullivan’s novels include her bestselling debut, Commencement (2009); The Engagements (2013), which has been published in 18 countries; and Saints for All Occasions (2017), a nominee for the New England Book Award.

In writing The Cliffs, Sullivan tapped her own experiences and family history to flesh out her characters. The oldest kid in an Irish Catholic family from the Boston suburb of Milton, she grew up hanging out under the dinner table, eavesdropping on adults, and trying to unravel what was really going on. “I come from a family who are not writers, but they are storytellers,” she says. “And they love to tell the same story 50 times, making it funnier or a little more interesting, putting themselves more at the center of it. So, me sharpening draft by draft is the same thing as my uncle telling a story a hundred times. And I feel like a lot of the stories I wrote—even in third, fourth, fifth grade—were about my family, and I’m still writing the hopefully more sophisticated versions of the same stories, 30-something years later.”

And like Jane, a pragmatic alcoholic who, Sullivan notes, “thinks she’s fine because she’s high functioning, until she’s not,” the author understands the perils of alcoholism. “I’m eight years sober,” she says. “I quit drinking when I was pregnant with my son, and then I said, You know what? It’s going to be best for me if I just stay on this path, because drinking has played a huge, destructive role in my family and a lot of other families.”

Motherhood is a recurrent theme throughout The Cliffs, and Sullivan says experiencing it firsthand has highlighted the tug of war between art and family life. “When I was pregnant for the first time, I remember thinking, Oh my gosh, I’m going to have a kid. I have to get perfect. I have to become a different person,” she says. “How am I going to do that? The answer is you don’t do that. You just do the best with whatever it is you have.”

For Sullivan, that means not stifling her artistic ambitions because she has children. “Why can’t we have both?” Sullivan asks. “Must we be punished for having our ambitions? My kids are 16 months apart. During Covid, they were feral. They truly looked like creatures who just came out of the forest. But I loved that time, because it was just us. No rules. No pressure. Just having fun in our little cocoon.”

It was during the pandemic that Sullivan learned to treat writing like a job. “It’s how I pay my mortgage, and, thanks to my kids, I can now write anywhere,” she says. “Before I had kids, I vividly remember being on a panel with two other women, who were both mothers. And I remember saying, ‘I need absolute silence. I need to know I have several uninterrupted hours to write.’ And I could feel these women looking at me like, Are you kidding me? Now, I totally get it. I’m writing when they’re at school or for 20 minutes before hockey practice. It’s a juggle for all of us. But they also help me tap into a lot of the joy of life, slowing down and noticing the little things. I mean, I spent all day yesterday at an arcade. I wouldn’t have it any other way.”

That is, of course, until the next little kernel of story begins to haunt her, begging to be told.