This is the story of SARS-CoV-2 and its fierce journey through the human population, as seen by the scientists who study its origin, its ever-changing nature, and its capacity to kill us. David Quammen expertly shows how strange new viruses emerge from animals into humans as we disrupt wild ecosystems, and how those viruses adapt to their human hosts, sometimes causing global catastrophe. He explains why this coronavirus will probably be a "forever virus," destined to circulate among humans and bedevil us endlessly, in one variant form or another. As scientists labor to catch it, comprehend it, and control it, with their high-tech tools and methods, the virus finds ways of escape.