Visit Frank Lloyd Wright’s home in Oak Park today and you will find time stopped at 1909-the year the 42-year-old architect and father of six notoriously left town for the Continent. “He had his own reasons for going to Europe,” says the writer Nancy Horan. “His marriage had been in trouble for some time, and he had to oversee publication of the Wasmuth portfolio,” which introduced Wright’s work to Europe.

And then there was the woman who accompanied him: Mamah (pronounced MAY-mah) Borthwick Cheney. “Mamah is not strongly emphasized in the tour of the Wright home and studio,” says Horan ruefully.

Horan has rectified that oversight with her first novel, Loving Frank (Ballantine Books, $23.95), out in August. Until she and her husband (the photographer Kevin Horan) moved to an island on Puget Sound last September, Horan had lived only a few blocks from 520 North East Avenue, an Oak Park house that Wright designed in 1903 for Edwin Cheney and his wife, Mamah. “I didn’t know what I was looking at for years,” she says.

But as she learned more about the headline-grabbing love affair, Horan-the mother of two children, as was Mamah-became intrigued by Mamah’s decision to abandon her family and follow Wright. “How could a mother do that?” she asks. “That made me pursue her point of view.”

Though Mamah stands at the center of Loving Frank, which ranges from Oak Park to Berlin to Taliesin (Wright’s grand Wisconsin home), the novel is inhabited by other real-life characters-including Wright himself. “It was daunting to put words into Frank Lloyd Wright’s mouth,” admits Horan.

As Frank and Mamah’s love affair advances toward its sad conclusion, the powerful writing imbues the tale with the terrible inevitability of a Greek tragedy. Ultimately, Loving Frank succeeds in making Mamah more than a footnote in the life of a great man, revealing all her strengths-and her flaws. “Do we need to love and approve everything our heroines do?” asks Horan. “We can learn from our sinners as well as our saints.”