From the bubonic plague to theoretical pathogens on other worlds, a sweeping look at the past, present, and future of mass infections and how we battle them. In this panoramic and up-to-date account, we learn how the Black Death, smallpox, the 1918 influenza pandemic, and other great epidemics have not only led to enormous suffering and mass death but have also contributed to the fall of empires and changed the course of history. We also discover how new infectious diseases such as HIV/AIDS and COVID-19 emerge and how we wage war against them.