Actually, I told her, I had. I'd stumbled across it while researching my last book, The King of California. The image had stuck with me, too. I remembered the way it showed cotton titan Bill Camp standing there, arms akimbo, while one of his farm workers tossed Steinbeck's novel into the flames.

"Well," Lee said, "have you heard about the librarian who fought the censorship?" That, I said, I didn't know anything about—but it intrigued me. "She was brave," Lee added. I promised to check it out. Thus began a four-year journey that turned into Obscene in the Extreme. Luckily, my first breakthrough came quickly. Soon into the project, I found the name of the laborer who had participated in the book burning back in 1939. On a lark, I typed "Clell Pruett" in the Internet White Pages, and up popped one result. There was a Clell Pruett in Missouri. I dialed the number, and a man answered.

When I explained what I was interested in, the voice on the other end didn't hesitate. "That's me," he said. It was then that I knew this had the potential to be a very special book with a remarkable cast of characters.

—RICK WARTZMAN