When his biology teacher Mr. Lynch assigns him to write a report about an infectious disease, Mitty has no idea what virus to research.

During a trip to his family's home in the Connecticut countryside that the Blakes visit nearly every weekend, Mitty finds some old medical books from Boston in 1902.

Inside the book, Mitty finds an old envelope containing 100-year-old scabs from Variola major (a severe form of smallpox) from an epidemic in 1902.

After reading an article from the Centers for Disease Control, Mitty begins to think that he has acquired smallpox from that exposure and is developing symptoms.

He soon learns that he does not have smallpox, though he is still hospitalized for the carbon monoxide poisoning and the injuries inflicted on him by his kidnappers.