When a new influenza virus emerges that is able to be transmitted between humans, it spreads globally as a pandemic, often with high mortality. Enormous social disruption and substantial economic cost can result. The 1918 Spanish influenza pandemic was undoubtedly the most devastating influenza pandemic to date, and it has been Webster’s life’s work to figure out how and why. In so doing he has made a remarkable contribution to our understanding of the evolution of influenza viruses and how to control them. A century on, Flu Hunter is a gripping account of the tenacious scientific detective work involved in revealing the secrets of this killer virus. Could a global influenza pandemic occur again? Webster’s warns: "... it is not only possible, it is just a matter of when."