How modern epidemiology was born through the unlikely rise of the plague rat. Today, rats are nearly synonymous with plague, but this association is surprisingly recent. For centuries, plague devastated populations without being linked to animals. So how did the rat become the symbol of one of history's deadliest diseases? In How Plague Got Rats, Christos Lynteris unravels this story by focusing on the Third Plague Pandemic, a global outbreak that began in China in the 1850s and claimed an estimated 15 million lives by the mid-twentieth century. This was the first major pandemic recognized by scientists as zoonotic—spread from animals to humans—and it marked a turning point in both medical science and global health. Through a gripping historical investigation, Lynteris explores how rats entered the medical imagination of the time. He reveals how scientific thinking about disease vectors evolved in tandem with colonial power structures as plague responses unfolded across Asia, Africa, and the Americas. From laboratory discoveries to imperial interventions, the rat became central not just to understanding plague, but to shaping new forms of epidemiological reasoning. This provocative book shows how zoonosis emerged as a politically charged concept in the context of empire and pandemic crisis. It is a powerful history of how science, society, and colonialism converged around a creature now inseparable from the story of epidemic disease.