The next big human pandemic—the next disease cataclysm, perhaps on the scale of AIDS or the 1918 influenza—is likely to be caused by a new virus coming to humans from wildlife. Experts call such an event “spillover” and they warn us to brace ourselves. David Quammen has tracked this subject from the jungles of Central Africa, the rooftops of Bangladesh, and the caves of southern China to the laboratories where researchers work in space suits to study lethal viruses. He illuminates the dynamics of Ebola, SARS, bird flu, Lyme disease, and other emerging threats and tells the story of AIDS and its origins as it has never before been told. Spillover reads like a mystery tale, full of mayhem and clues and questions. When the Next Big One arrives, what will it look like? From which innocent host animal will it emerge? Will we be ready?