We all need a bit of magic from time to time,” Maud Gage Baum says to the young Judy Garland in Elizabeth Letts’s new novel, Finding Dorothy (Ballantine, Feb.). Maud—the widow of Wizard of Oz creator L. Frank Baum and the indefatigable central character of Letts’s story—is a woman profoundly familiar with both the importance of magic and the endless challenges of creating it. Warm, articulate, and fiercely intelligent, Letts feels as vibrantly present as if she were sitting across the table, though our conversation is being conducted remotely—Letts in her California home, me in North Carolina.

As a fiction writer, Letts is of course a magic maker. But like Maud Baum, she has a practical side. Though she was a passionate reader who knew from the age of seven or so that she would write a book some day, she honed her skills at other endeavors first. After graduating from college, she taught English in a Moroccan high school as a Peace Corps volunteer, then attended the Yale School of Nursing and became a certified nurse-midwife. Her literary aspirations came back into focus when an old friend mentioned that she had written a book. “Wait,” Letts remembers thinking, “that’s my dream, too!” In her 40s by that time—coincidentally, the same decade of life in which Baum wrote The Wonderful Wizard of Oz—she realized it was now or never.

Letts happened upon the story at the heart of her first nonfiction book, The Eighty-Dollar Champion (2011), when she came across a memorable image of the award-winning show horse Snowman. As a passionate equestrian herself, she was no stranger to the world of horses. The detailed research involved in writing historical nonfiction was familiar as well: Letts had majored in history during her undergraduate years at Yale, and her professional work had shaped her ability to master complex bodies of information. The process of writing narrative nonfiction, however, felt a bit daunting at first. “Your reader wants a fascinating story, but you’re stuck within the context of what really happened,” she says. “It felt like taking an old newspaper, tearing it up into thousands of tiny pieces, and then trying to reassemble them in a fresh yet still accurate way.”

Nonfiction offered Letts much satisfaction—but fiction, she says, opened a whole new door. “I took a lot of inspiration from Frank Baum when I was writing Finding Dorothy,” she says. “He believed that there was only a flimsy veil between other worlds and our own. Fiction allows me to push aside that veil. Rather than merely telling readers about my characters, I can step into an imaginary world and inhabit it right beside them.”

As a child experiencing Oz through Baum’s book and the classic MGM film it inspired, Letts counted Dorothy as an invisible friend. Decades later, she was reading the book aloud to her son when its unusual depiction of female characters captured her attention. Dorothy, though only a young girl, was wiser and more whole than the male characters sharing her journey through the Emerald City; whether for good or ill, even the witches were striking in their power. Knowing almost nothing about Baum, Letts found herself wondering how a man who lived much of his life in the 19th century came to imagine such forceful and even subversive figures.

One answer, Letts found in her research, lay in Baum’s wife. Maud Gage Baum, whom he married in 1882 and to whom the first of his 14 Oz books is dedicated, was the daughter of Matilda Joslyn Gage, an author and suffragist who fought for female enfranchisement alongside Elizabeth Cady Stanton and Susan B. Anthony. As she researched more, Letts was struck by how prescient Matilda Gage’s writings were, offering perspectives that still feel strikingly modern today. Though Maud didn’t share her mother’s activist spirit, she had a formidable strength of her own. “Looking at these women, I began to understand how Frank Baum wrote such remarkable female characters. A really new way of thinking about women’s roles was percolating in the Baum household, and you can see reflections of it in Oz once you know to look for them.”

Matilda, Maud, and Baum himself were all extraordinary characters, but Letts still didn’t see a book in the material. That changed when she came across a photograph of Maud on the MGM studio lot with the teenage Judy Garland. Letts discovered that Maud, widowed and in her 70s by that time, served as a consultant during the filming of the movie. But despite the myriad volumes devoted to Oz and its creator, virtually all of which she eventually read, Letts could find almost nothing about Maud’s time on set or her relationship with Garland. “I wanted to know what happened,” she recalls, “and the only pathway to knowing what happened was through fiction.”

Letts’s novel moves fluidly between two phases of Maud Baum’s life: her long relationship with Frank Baum (from their meeting in 1880 through the completion of The Wonderful Wizard of Oz in 1899) and the adaptation of the book into film two decades after Frank’s death. The larger-than-life Baum—a ferociously inventive, optimistic, and talented man who failed in theatrical, publishing, and retailing ventures before Oz became a bestseller in 1900—comes effervescently to life in Letts’s pages, and his creative vision forges the most obvious link between her novel’s two narratives. Yet it’s a chain of female mentorship that forms the most memorable connections in the novel. As the younger Maud raises four sons and keeps her family afloat amid endless financial vicissitudes, she feels a deep bond with Magdalena, her sister Julia Carpenter’s daughter and one possible inspiration for the character of Dorothy. “The Carpenters homesteaded in Dakota Territory, where the Baums also lived for a time. Julia Carpenter’s diary offered me so many small useful details, and I’m grateful to have had the chance to explore the area where they lived myself,” Letts says. “When I visited the library in Aberdeen, where Frank opened a short-lived store, the staff let me sit and look through boxes of Baum family memorabilia spanning decades of their lives. Maud’s lace and stationery, lots of family photographs: it was touching those things, and seeing those places, that really brought the story to life for me.”

Decades later, on the bustling set of Oz, Maud attempts to persuade the filmmakers to stay true to her husband’s vision and forms a friendship with the young Judy Garland. Unlike Garland’s own mother, whose driving ambition precluded maternal succor, Maud appreciates Garland’s vulnerability, as well as her gifts. Giving rich voice to “Over the Rainbow” with a profound and uncannily adult yearning even as she was manipulated by the adults around her, Garland represents a kind of longing Maud recognizes. “Garland never really got out from under the pain of her early life. Yet at only 15 or 16, she made immortal a song that really embodies the spirit of hope. That was an incredible achievement, and something that I really wanted to understand in writing about her.”

Though its publication coincides with the 80th anniversary of the 1939 Oz film release, Finding Dorothy is timely for another reason. Letts had finished the novel by the time #MeToo hit the headlines, but it presages some of the movement’s themes, from the predation of powerful film studio executives to the healing available in female support. As our conversation ends, I tell Letts that for me, the book’s chief women seem to be providing sustenance to daughters both seen and unseen, present and future, related by blood or just by spirit. “That’s what we do,” Letts says. “Nineteenth-century women reformers, those of us today—we just kind of kick the ball down the field, trying to make a difference for the next generations. This issue, of how the women before us affect our lives, helped draw me to Maud’s story. I’m glad to find that comes across in my book, and I’m hoping this will be a moment when we really move forward as women.”