On September 13, 1900, thirty-four-year-old physician Jesse Lazear believed he was on the brink of a scientific breakthrough that would put an end to yellow fever, the worst epidemic scourge of nineteenth-century America. Dr. Jesse Lazear, a member of the US Yellow Fever Board working in Havana, was working on a radical theory of transmission, which placed the lowly mosquito at the center of one science's most elusive riddles. Shortly after being bitten by a lab mosquito known to be infected with yellow fever, two of Lazear's co-workers had fallen ill. Encouraged by this success, the ambitious young surgeon put himself at risk, allowing an infected mosquito to bite him. In less than two weeks, after several days of delirium and black vomit, Jesse Lazear was dead. This film documents the research of intrepid Cuban scientist Carlos Finlay and the efforts of Major Walter Reed and his medical team, some of whom put their own lives on the line to eradicate yellow fever.