In 1926, Father Charles Coughlin established The Shrine of the Little Flower in Royal Oak, Michigan. Over the course of the next four decades, Coughlin built this small Catholic church into a large, ornate, highly profitable and, to many, infamous mecca. Coughlin began his radio career in the late 1920s with a weekly broadcast known popularly as "The Children's Hour," in which he told biblical stories to children.

While these early programs were merely the tame sermons of a parish priest, they soon became paranoid political tirades. The program became known as "The Hour of Power," and by the late thirties it was the most controversial broadcast in America. Coughlin used the program and the new medium of radio to command an army of the disaffected.

By giving expression to their basest fears and hatreds, he virtually created the "lunatic fringe," a new American phenomenon that inspired hate mobs to go on violent rampages and encouraged self-styled fascist organizations like the Christian Front and the German-American Bund to plot the downfall of the federal government and the disenfranchisement of American Jews.

Based on more than twenty years of research, including unprecedented access to FBI and Catholic Church archives, Radio Priest is a definitive and timely biography, including revelations of Coughlin's ties to the Nazis and to fascist leaders such as Mussolini and the English aristocrat Oswald Mosley.

In April 1995, after home-grown American extremists were arrested for bombing the federal building in Oklahoma City, stories about obscure radio personalities like Mark Koernke (Mark from Michigan) began appearing in The New York Times, asking if slogans like Koernke's "I love my country. I fear my government" could have incited such violence. But as Donald Warren argues in Radio Priest, to understand the paranoid fringe, one must understand its populist, deeply American roots.