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 No. 1 bestseller, flying off store shelves at a rate of 10,000 copies a week. 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 that fit of censorship, a moment when several lives collided as part of a larger class struggle roiling the nation. It is a superb historical narrative that serves as an engaging window into an extraordinary time of upheaval in America, when as Steinbeck put it, “A revolution is going on.”