Back in 2013, when Jeanine Cummins began research for American Dirt, her new novel tracing a Mexican woman’s harrowing flight to the United States, immigration and border security were not quite the hot-button issues that they are now. But as the granddaughter of a Puerto Rican woman and the wife of an Irish immigrant (who was undocumented until he and she married), Cummins was already uncomfortable, she says, with the way many Americans viewed immigrants.

“It’s so easy to think of immigrants as other,” she comments, seated in a conference room at the offices of Flatiron Books, which will publish American Dirt in January. “I think it’s all the easier to do when you don’t have access in an intimate way to the stories of people who are coming here. I definitely wanted to tell a story that would put humanity and empathy front and center in a way it has not been in the national dialogue up till now.”

Cummins wants the migrant characters in her story to be recognizable and relatable to U.S. readers. Her protagonist, Lydia, is an educated, middle-class woman who runs a bookstore in Acapulco, deliberately countering the stereotypical image of a migrant. “We treat immigrants at the border like one brown homogenous glob,” she says. “But they’re coming from many different socioeconomic circumstances, different countries, often different languages; for many indigenous people, Spanish is not their first language. I always want to make sure my reader has an easy entrance into the story, and most American readers have relatively comfortable middle-class lives. Lydia serves as a lens through which readers can observe other more typical migrant stories, because she comes from a life more familiar to us.”

Lydia is forced to flee Acapulco with her eight-year-old son, Luca, after her journalist husband exposes a local drug lord and is later murdered along with 15 other members of her extended family. The drug lord, Javier, patronized Lydia’s bookstore, and they had been friends, though Lydia was unaware of his crimes before his exposure; his personal animosity follows her as she heads north, and it comes to a dramatic resolution shortly before she crosses the border.

Cummins’s strong plotting and knack for building suspense were evident in her previous novels, so it’s a surprise to hear her say those things don’t come easily. “I think my strengths as a writer are description, character development, and research,” she says. “I have a very difficult time with plot, so I’m hyper-aware of it. I talked at great length with Amy Einhorn [her editor] about pulling the threat of Javier through the book so that Lydia never felt safe from him. The final reckoning with Javier actually came from a meeting with the producer who bought the movie rights. He wanted them to meet face-to-face, which I was very reluctant to do, but I did realize after talking to him that there should be a moment when Lydia has some kind of final say.”

Cummins has a no-nonsense attitude about the nuts and bolts of writing and publishing, which comes from a decade on the sales force at the New American Library, which published her first three books. “I loved being in the industry—being around book people all day, every day,” she recalls. “But I always hoped to write. Then my brother Tom asked me to write a book with him.”

That book, 2004’s A Rip in Heaven, was a memoir of the horrific night in 1991 when 19-year-old Tom and two female cousins were accosted on a bridge in St. Louis by a gang of four men, who raped the two girls and tossed them off the bridge to their deaths, then forced Tom to jump. Cummins’s then-boss, Norman Lidofsky, president of sales at NAL parent company Penguin USA, was instrumental in getting the siblings a contract. But Tom ultimately felt he couldn’t face the exposure of publication, so Cummins found herself the sole credited author and spokesperson for her family’s trauma on the book’s press tour.

“I had to go out and talk to people about the worst moment in my life,” says Cummins, who was 16 at the time of the murders. “It was really tough, and I knew I never wanted to write anything like that again. But I equally knew from this experience that social justice was my thing—that the anger I feel when I think a story is being misrepresented is what I want to express. It is always my catalyst as a writer to try to tell a story that can sometimes make people understand a point of view they were unaware of before. I sometimes feel you can do that better in fiction, because people come into fiction with a more open heart.”

Cummins moved on to fiction with 2010’s The Outside Boy, set among a group of itinerant Irish known as Pavees, and 2013’s The Crooked Branch, which juxtaposed a mother’s struggle during the Irish potato famine with the story of a contemporary New York City woman beset by feelings of inadequacy following her daughter’s birth. She has only good words for her time at NAL as an employee and author. But, she says, “it was no longer the right fit for me, and we knew that even before American Dirt was finished. I had talked about it with my agent, Doug Stewart at Sterling Lord, and I think my editor at NAL [Claire Zion] was in agreement that my time there had run its course and I was ready for something new. She had an option on this book, she read it, and she wrote back with the most gracious exit plan. The parting of ways was incredibly amicable.”

American Dirt went to auction. “I had phone meetings with 12–15 editors, and many of them I loved, but Amy stood out,” Cummins says. “She was the only one who rolled up her sleeves; we spent our hour talking about how to edit the book. I ended up adding about 40,000 words after she bought the book, and I feel it is so much better because of her. She’s so smart; every time she gave me an edit, I would almost be embarrassed—I would say, ‘Why did I not see that before?’ She has a way of homing in on exactly the thing that’s missing or isn’t exactly right, and of really articulating what you need to do. The final third of the book, the border crossing, was just too quick, and she recognized every moment I had glossed over or rushed. Amy gets me in a way that feels tremendously exciting.”

Einhorn will edit Cummins’s next novel as well, despite her recent move to Holt as president and publisher. “I don’t know exactly how the contract is finagled,” Cummins says, “but she will be my editor either at Flatiron or Holt. About the new book, I can say what very little I know, which is that it’s going to be about Puerto Rico. I don’t have any idea of the narrative arc yet, but there are so many social justice issues in Puerto Rico that are being underreported right now, it definitely feels like fertile ground for a new novel.”