Understanding Koch's postulates, including how they are used to study the spread of disease within a population, is central to the teaching of microbiology. These concepts are often presented and discussed with little or no historical background, and as a result students fail to appreciate how the field has developed from past to present. We designed a lesson based on the story of Typhoid Mary to engage students in the learning and application of Koch's postulates in the field of epidemiology and provide insight into the interplay between scientists and the public as illustrated by this episode. The lesson uses an interrupted story technique in which students watch a documentary about Typhoid Mary, with pauses to discuss the events and engage in a role-play to reenact Mary's trial. The purpose is to improve student understanding of central concepts and to foster a deeper understanding of issues associated with the nature of science (NOS), such as how the process of science is influenced by culture and society (and vice versa). This lesson plan was created for a college-level microbiology course for non-majors, but can be easily modified for use in high school settings.