When Janice Nimura came across Emily Blackwell in the Sophie Smith collection at Smith College in 2015, she was intrigued and looking to fall in love with a project. Emily led her to Elizabeth, the older Blackwell sister, who in 1849 became the first woman in the U.S. to get a medical degree (Emily was the third). In January, Norton will publish The Doctors Blackwell: How Two Pioneering Sisters Brought Medicine to Women—and Women to Medicine.

“It felt like an arranged marriage,” Nimura says of writing the story of the Blackwells. “I wasn’t swept off my feet, but felt if I committed, the love would grow. Their story resonated with things I wanted to spend time with.” The Blackwell sisters became her “personal hobby horse,” she says. “I imagined them sitting on my stoop waiting to be invited inside.” Nimura says she wanted to rescue the sisters from the well-scrubbed idea of them, noting that their story was complex and they were complicated women. “If you look for Elizabeth Blackwell, you find children’s books or nothing,” she says.

The sisters were American, but born in Bristol, England (Elizabeth in 1821; Emily in 1826), into a progressive, feminist, antislavery family, the two girls among nine siblings. Their lives spanned the 19th century, and they interacted with everyone of any importance in the century. Together, in 1857, they founded the New York Infirmary for Women and Children, the first hospital for and staffed by women.

“It was a challenge for women to establish legitimacy in the medical field, to define themselves,” Nimura says. “It’s a great story, because the past is not always pretty. The sisters, for example, were not suffragettes. They believed women had to liberate themselves.” Elizabeth advanced education for girls, but also had a strong investment in Christian morality and opposed both prostitution and contraceptives. But these were “19th-century border-crossing women,” Nimura emphasizes. “Emily had a female partner, also a doctor; they were hard-core careerists.”

Nimura admits that the Blackwell sisters project “was terrifying.” She was confident, she says, in writing her first book—Daughters of the Samurai (Norton, 2015), the story of five young women sent by the Japanese government to the U.S. in 1871 to learn Western ways—because it was a story no one was familiar with and she had a personal connection (Nimura’s husband is Japanese and she’s lived in Japan). With the Blackwells, she “felt exposed,” she says, emphasizing, “I am not a historian, but an independent scholar.”

After she found the sisters in 2015, Nimura says she “sat with them, did a proposal a year later, and sat with that.” She handed in the first draft to Rob McQuilkin, her agent at the literary agency Massie & McQuilkin, in the fall of 2016.

“It was a knockout proposal,” McQuilkin says. “A complex subject, but Janice didn’t make it obvious that it was complicated. The confidence was on the page, sure-footed in scholarship and prose.” What Nimura has done, McQuilkin says, is introduce the women to the present. “Elizabeth,” he says, “was not interested in public health, but in making a point. Emily liked the service; she liked treating patients. The Blackwells are an example of teamwork; they relied on each other as political allies as well as sisters.”

Everyone wanted the book when it went out on submission, McQuilkin tells me. There were 10 bidders, but The Doctors Blackwell went to Norton executive editor Alane Mason, who had worked with Nimura on Samurai. “Alane was an under-bidder,” McQuilkin says (calling the deal a nice six figures), “but Janice had partnered well at Norton, and it was an arcane subject. Alane knew she would bring it home.” He also believes it’s a good time for a book highlighting women: “despite women’s achievements, sexism has continued.”

The summer of 2017 was the summer of the “nasty woman” (as Donald Trump had called Hillary Clinton during a presidential debate in 2016). Nimura, too, thought it was a good time for a story about complicated women. And Nimura can claim prescience: Trump is currently using the word nasty to refer to another complicated woman, Joe Biden’s running mate, Kamala Harris.

Mason, meanwhile, had been nagging Nimura to find another subject after publishing Samurai in 2015, and she says that as soon as she saw the proposal for The Doctors Blackwell, she wanted it. “To make the sisters human, to overcome the formality of their photos was not easy. These women were not perfect,” Mason says, adding that Nimura did a magnificent job.

She considers Nimura the ideal author. “She should write a guide for authors on how to behave through the editorial process,” Mason says. “She’s so easy to work with: savvy, wonderful, dedicated, and her research is fantastic and original. No one knew the story of the first women doctors. When you think medicine, you think male, white coats. It was monumental to crack this.”

I have my own attachment to the Blackwell sisters. I was born at Women’s Infirmary, delivered by a woman doctor who was legendary in local circles and ran for mayor of New York City on the Communist Party ticket in the 1950s. Thank you, ladies.