Few books have caused as big a stir as John Steinbeck’s The Grapes of Wrath, when it was published in April 1939. By May, it was the nation’s number one bestseller, but in Kern County, California—the Joads’ newfound home—the book was burned publicly and banned from library shelves. Obscene in the Extreme tells the remarkable story behind this fit of censorship.

When W. B. “Bill” Camp, a giant cotton and potato grower, presided over its burning in downtown Bakersfield, he declared: “We are angry, not because we were attacked but because we were attacked by a book obscene in the extreme sense of the word.” But Gretchen Knief, the Kern County librarian, bravely fought back. “If that book is banned today, what book will be banned tomorrow?”

Obscene in the Extreme serves as a window into an extraordinary time of upheaval in America—a time when, as Steinbeck put it, there seemed to be “a revolution . . . going on.”