Replete with terror, passion, and hope, this gripping narrative history explores the intricate mysteries of medieval Europe through the lives of the great heretics whose beliefs and practices challenged the teachings of an all-powerful church. Five centuries of social and spiritual turmoil are covered through a vivid and telling mix of events, personalities, and ideas. A host of figures are discussed in detail, including Bogomil, an obscure priest from the Balkans who introduced Manichean ideas to parishioners; Henry the Monk, who eluded capture and prepared southern France for the Cathars; Marguerite Porete, the great mystic who was burned at the stake; Fra Dolcino, whose brigand followers terrorized northern Italy; and the heralds of the Reformation, John Wyclif and Jan Hus. By the end of the Middle Ages, the courageous lives and beliefs of these and the other heretics discussed had transformed the religious, cultural, and political map of Europe.