On the 25th anniversary of the first diagnosed cases of AIDS, FRONTLINE examines one of the worst pandemics the world has ever known. After a quarter-century of political denial and social stigma, of stunning scientific breakthroughs, bitter policy battles and inadequate prevention campaigns, HIV/AIDS continues to spread rapidly throughout much of the world. Through interviews with AIDS researchers, world leaders, activists, and patients, FRONTLINE investigates the science, politics, and human cost of this fateful disease and asks: What are the lessons of the past, and what can be done to stop AIDS?