A few days a week, rain or shine, author Sarah Pekkanen leaves her apartment in Bethesda, Md., and walks with her laptop to her favorite vegetarian restaurant, where she sits down for a meal. Between bites of food and sips of wine, she writes—and listens to strangers talk.

“You really get an insight, especially if somebody’s on a date,” she says. “You can hear how they’re portraying themselves and how a person acts when the other person goes to the bathroom. It’s fascinating.”

Pekkanen, who has the easy manner of someone who’d rather be listening than talking, is deeply curious about people (“I geek out on psychology,” she says) and relishes juicy stories about infidelity and murder. Her nine standalone books—which include The Opposite of Me, her 2010 debut, and the 2023 thriller Gone Tonight—have together sold 550,000 copies, according to her publisher, St. Martin’s. She’s also the coauthor, with Greer Hendricks, of four psychological thrillers that have sold a combined three million copies and include the 2018 blockbuster The Wife Between Us, about a woman who spies on her ex-husband’s fiancée, which has been translated into 36 languages.

House of Glass—her second solo thriller, out in August—concerns divorcée Stella Hudson, a best-interest attorney working on behalf of children in tense custody cases. Hudson’s latest client is nine-year-old Rose Barclay, a girl whose wealthy parents, Beth and Ian, are divorcing, and who may have witnessed the death (or was it murder?) of her nanny, Tina. It’s hard to know what Rose actually saw, because she has stopped speaking, and Hudson has to figure out how the nanny died and if Rose’s parents are to blame, or if Rose is the real threat. As the story unfolds, Pekkanen expertly tracks Hudson, who’s dealing with childhood trauma related to the death of her addict mother, and Rose, the eerily quiet child at the center of the mystery.

The idea for House of Glass came to Pekkanen while she was on a bus with the mom of her son’s friend—a woman who worked as a best-interest lawyer. “I thought, I have to write about this kind of character,” Pekkanen recalls. “You get to go deep into another family’s life; they tell you their secrets. I knew that with the right plot it could be a fascinating story.” And having a strong lead was important. “I like to write about women who use intelligence and grit to get out of difficult situations. I don’t write damsels in distress. I like complicated women.”

Pekkanen’s ability to explore the dark side of seemingly perfect worlds is one of the things her editor, Jennifer Enderlin, enjoys most about her fiction. “Sarah is extremely observant and listens in a way I’ve almost never seen people listen,” Enderlin says. “Her writing is deep psychologically, and she really explores people’s behaviors and what makes them tick.”

Born in New York City in 1967 and raised in Bethesda, Pekkanen was consumed by her own thoughts from a young age. In grade school she would often wander into the wrong classroom. “I was constantly daydreaming, still am,” she says. “Even now, if I drove anywhere without Waze, I would be, I don’t even know, in Canada.”

After graduating from the University of Maryland in 1990 with a journalism degree, Pekkanen backpacked across Europe for four months, then went to work as a reporter covering D.C. politics, eventually landing jobs at The Hill and the Baltimore Sun. She got married in 1994 and left journalism in 1999 to raise her sons but couldn’t live without writing. “I was getting my ass kicked every day with the kids,” she says. “But it was either sleep more than five hours or write.”

Pekkanen worked on a novel in the 2000s at soccer practices and while waiting to pick the kids up from school. That manuscript was ultimately rejected, but she kept at it, and since publishing The Opposite of Me, she’s written a book every year. Her lucrative four-book collaboration with coauthor Hendricks—which began in 2018—was a career turning point, moving her into the thriller space. Splitting with Hendricks after 2022’s The Golden Couple felt like a breakup, but a necessary one. “We’re still friends but we don’t talk about writing anymore,” Pekkanen says. “We’re doing our own things. Yeah, there was sadness, but the collaboration ran its course.”

Margaret Riley King, Pekkanen’s agent, is impressed by the author’s ability to set new challenges and keep it moving. “Sarah is creative, ambitious, and wildly prolific,” King says. “She’s an ideas person and works incredibly hard.”

But Pekkanen admits that hard work and writing isn’t a choice for her. “If I’m not working on a project, I don’t know what to do with myself,” she says. “I feel itchy and restless.” Beyond fiction, she loves screenwriting—she’s written several scripts, including one for The Wife Between Us for Amblin Entertainment—and just finished a House of Glass TV pilot.

I like to write about women who use intelligence and grit to get out of difficult situations. I don’t write damsels in distress. I like complicated women.

In the past few years, Pekkanen’s life has been about collaboration and transition. In 2018, she and her husband divorced after 24 years. After they separated, they continued to live together for five years, for financial reasons and for the sake of the kids.

Now living on her own, Pekkanen’s exploring her freedom and stretching creatively. A self-described adrenaline junkie, she leans into adventure: she scuba dives, climbs mountains, and she once bought a Groupon for a flying lesson to cure her aerophobia. She also founded a nonprofit in India in 2023, India Street Paws, to help street dogs, and is traveling there this summer for a ribbon-cutting ceremony. She longs to be of service to the world—and, above all, wants to keep writing. “I love meeting people and hearing their stories,” she says.

She doesn’t mind a little eavesdropping either. After all, you never know what you’ll discover.

Elaine Szewczyk’s writing has appeared in McSweeney’s and othernpublications. She’s the author of the novel I’m with Stupid.