"I don’t have a mother tongue,” Tatiana de Rosnay says via Zoom from Paris. “I learned French and English at the same time. My English mother spoke to me in English; my French father spoke in French. I feel English in France and French in England.”

For some writers, this slightly unusual relationship to language could present challenges, but not so for de Rosnay. She started writing what she calls her “little stories” in English when she was in a bilingual school—“Perhaps because the books I really enjoyed as a child were in English, like Poe and Dickens, so English fueled my appetite for reading and writing”—but soon realized she could write in either language. Then De Rosnay, who has more than 20 titles to her name, came up with a unique process suited to her linguistic skills: writing simultaneously in both languages. She calls the technique “auto translation” or “auto-adaption” and first used it for her 2021 novel Flowers of Darkness.

“I have written some books directly in French, others in English,” she says. “There is invariably a pang of regret from having to choose one over the other. I decided to experiment, writing simultaneously in both languages. Two documents opened up on my computer: one in English, one in French. My writer friends stare at me and say, ‘How do you do this?’ But early on there was a complicated moment when I was told I couldn’t translate myself, and I cannot bear to be translated, so this is my solution.”

De Rosnay used this process for her latest novel, Blonde Dust—out in June from Grand Central. It’s a departure from the author’s usual European settings and characters: the novel follows Pauline, a French American chambermaid at the fabled Mapes Hotel in Reno, Nev., in 1960, whose dream of becoming a veterinarian was derailed by an unexpected pregnancy and whose life is changed when she crosses paths with Marilyn Monroe.

Born in Neuilly, France, in 1961, de Rosnay had a nomadic early life that mirrors her relationship with languages. When she was 10, her family moved to Boston, where her father taught biology and computer graphics at MIT—this, she says, explains her “slight” American accent. The family returned to Paris in the early ’70s, and then de Rosnay moved to the U.K. in 1981, where she got a BA in creative writing and comparative literature from the University of East Anglia. In 1984, it was back to Paris, where she worked as a journalist and critic, got married, and still lives today.

In 1992, de Rosnay published her first novel, which was written in French. “I had no agent then,” she says. “I had a recommendation from my dad, who knew a couple of publishers.” She went on to publish seven more books in French while working as a freelance journalist for French Elle and Psychologies.

And then in 2007 she published Sarah’s Key, a smash hit, written in English, that sold more than 11 million copies worldwide, per Macmillan, and took her career to another level. “I don’t think any other book that I will ever write will have that success, but at least I had it,” she says. “I can say it happened once in my life and made my reputation.”

De Rosnay notes that the novel almost didn’t see the light of day. “My books weren’t doing that well and weren’t translated, and my publisher turned the book down. Sarah’s Key was written in English, and St. Martin’s gave me my chance, which was miraculous.”

St. Martin’s had been de Rosnay’s American publisher since Sarah’s Key, but Blonde Dust was sold to Grand Central by her new British agent, Susanna Lea. The author says she’s happy to be with a new publisher who is so enthusiastic. “This is a whole new direction for me.”

In Blonde Dust, Pauline, who is enamored of Nevada and its wild horses, spends her time helping activists preserve the state’s mustangs. She also works at the Mapes Hotel under the sour Mildred and is flummoxed when she’s taken away from her usual duties and asked to clean suite 614. Thinking the rooms empty, Pauline is surprised when “Mrs. Miller” emerges stark naked from the bedroom. Pauline doesn’t know she’s just met Monroe, who is in town to film The Misfits. But the two women soon form a bond as Monroe’s marriage falls apart and Pauline gains confidence under the tutelage of the movie star.

De Rosnay says French publisher Albin Michel first encouraged her to write about Monroe—a suggestion that was initially met with some reluctance. “There was so much stuff about Marilyn Monroe. I’m looking at a stack of probably 80 books right now. I’ve always been a fan, but everything’s been written about Monroe, everything’s been said about her, so my first response was, I’m really sorry but I don’t have anything new to say.”

But then de Rosnay came across a video of the Mapes Hotel imploding—the building was demolished in January 2000—and thought about telling the story of someone who had worked at the hotel in the 1960s, whose life had been impacted by it. “All of a sudden, I had my story,” she says. “I had the French chambermaid and the mustangs and the Wild West. It’s interesting what goes on behind closed doors in hotels, and here I had these two women, one in the shadows and one in the limelight. Writing this book, I felt I was sort of galloping away on a mustang and discovering a universe I had never written about before. Most of my research was about Nevada—where I’ve never been—in the ’60s rather than about Monroe.”

De Rosnay notes that she didn’t have to invent anything about the iconic actor: the drinking and pill popping and unhappiness are all well-known. “What was interesting was to see her through the eyes of a young girl who doesn’t really know who she is—and is not interested in movie stars but who will come into her own because this older, experienced woman will teach her how to gain confidence in herself.”

And while most of de Rosnay’s books—regardless of the language they are written in—have dark themes and ambiguous endings, the author says her latest is a bit different: “Blonde Dust is the first time in my life that I’ve written something positive. I wouldn’t say it’s a feel-good book, but it’s the story of someone who is going to make it.”