In 1348, at the age of twenty-two, Joanna I, the queen of Naples, stood trial before the pope, accused of murdering her cousin and husband, Hungarian prince Andrew. Arguing her own case in Latin, she won her acquittal, and went on to become the only female monarch in her time to rule in her own name; she presided over one of Europe's most prestigious and influential courts for more than thirty years—until she herself was murdered. For the first time, Nancy Goldstone tells the full story of one of the most courageous and accomplished women in history, painting a captivating portrait of medieval royalty in all its splendid complexity.