The prologue begins by introducing Paul Lewis, a medical scientist and lieutenant commander in World War I. Lewis is studying the violent symptoms and frightening spread of a new disease. Although unsure of the cause of the disease, and how to cure it, Lewis correctly believed that the mysterious disease was influenza.

Stepping back from Paul Lewis, author John M. Barry gives an overview of the pandemic. The virus emerged in 1918, likely in the United States, and faded by 1920. In that time, it killed “more people than any other outbreak of disease in human history,” with the estimates of the worldwide death toll ranging from twenty-one to one hundred million.

Tragically, the virus even struck down young adults in their twenties and thirties. Most of the deaths occurred in only the first twenty-four weeks of the virus’s spread. While it killed more people than the Black Plague, there are similarities between the diseases, both in their scope and in the reactions they provoked.

The story of the 1918 influenza “is not simply one of havoc, death and desolation.” It is not simply “a war against nature” against the backdrop of World War I. Barry writes that “it is also a story of science, of discovery, of how one thinks, and of how one changes the way one thinks.”

The 1918 pandemic was “the first great collision between nature and modern science.” The heroes of the story are the men and women who prepared for a possible pandemic and who pursued “grim, determined action” when the disease did strike.

To tell this story, it is necessary to trace the shift in medicine in the United States. The study of medicine experienced a revolution in the decades before World War I, first in Europe and then in the United States. Until a “virtual handful of leaders” transformed American medicine, it significantly lagged behind other Western countries. By the time World War I erupted, American medicine had become “the best in the world.” When the influenza pandemic hit, these medical scientists demonstrated courage and a commitment to build a “body of knowledge” that would point to the future of medicine.