Who were the flagellants? What were Bills of Mortality? Why did plague doctors wear beak-like masks? For hundreds of years, bubonic plague, a devastating disease, has affected the world's population. This book looks at the three plague pandemics, which were responsible for the deaths of millions of people. Find out how doctors tried to cure the Black Death and how scientists eventually discovered that rodents such as rats and a bacterium called Yersinia pestis caused the plague.