Barbara Kingsolver started working on her new novel,"The Lacuna," in February 2002, when a"long-term ache" to write about the estrangement of art and politics in the U.S. was fired up by the events that followed 9/11. The word lacuna means a gap or interval, but it also has botanical and anatomical meanings; before Ms. Kingsolver became a writer, she earned a master's degree in ecology and evolutionary biology. The author's Africa-set 1998 novel"The Poisonwood Bible" was an Oprah's Book Club selection; the nonfiction"Animal, Vegetable, Miracle" was a best seller in 2007. In"The Lacuna," Ms. Kingsolver embeds a fictional character, Harrison Shepherd, in Mexico in the 1930s, when the lives of Marxist theorist and assassination victim Leon Trotsky and the married painters Diego Rivera and Frida Kahlo intersected, artistically, politically and sexually.

The Wall Street Journal: What attracted you to that time and place?

Ms. Kingsolver: For the past 20 years, I have often found myself on the defensive when people ask if it's appropriate to write novels about power imbalances related to gender or ethnicity. I've wondered why art and politics seem to have an uneasy relationship in the U.S., while they travel hand in hand in most of the world. People elsewhere look to art and literature for commentary on the social and political aspects of the culture.

Maybe it's like keeping church and state separate.

I had a hunch it was related to historical events... the McCarthy era and that period of ferocious political censorship of art. Art and politics were forced apart at that time, and we've never gotten over it.

Then why is so much of this book set in Mexico?

When I started uncovering this story, I saw how World War II and postwar events affected this country differently from the way they affected Mexico. I believe Mexico maintains an ongoing openness to self-criticism. Mexico has a clear sense of itself as a work in progress; America thinks of itself as a finished product.

I thought maybe you had come to the story through Frida Kahlo; she wasn't your main character, but she was mesmerizing.

Originally, I had no intention of bringing in Frida Kahlo at all. But when I walked around Diego Rivera's house, she was everywhere. She was a remarkable person who had a lot to say about the meaning and purposes of art. She took over every scene I put her in.

Was it a challenge to write from a male character's point of view?

I needed a character who could travel from the drumming heart of the Mexican Revolution into World War II and postwar America. ... A woman in that place and time couldn't have done what he did.

How did it feel to play around with real historical figures?

I took everything I could from the public record. Trotsky talked and wrote a lot about himself. Frida kept journals, Diego wrote an autobiography. I could get very detailed itineraries of what they did and said. I was true to all that, down to the detail...