The DNA double helix, penicillin, the X-ray, insulin: these are routinely cited as some of the most important medical discoveries of the 20th century. And yet, the 1949 discovery of lithium as a cure for bipolar disorder is perhaps one of the most important—yet largely unsung—breakthroughs of the modern era. Here psychiatrist Walter Brown reveals two unlikely success stories: that of John Cade, the Australian physician whose discovery would come to save an untold number of lives and launch a pharmacological revolution, and that of a miraculous metal rescued from decades of stigmatization.