As Jen pores over her introductory biology textbook, she falls asleep and enters a nightmarish world in which bacteria and viruses dwarf human beings. This engagingly written case explores the differences between viruses and bacteria while teaching about the basic components and “life” cycle of a T-even bacteriophage. The case includes a follow-up assignment in which students explore the risks and potential benefits of using bacteriophage to control bacterial disease. The case is appropriate for general biology and microbiology college courses as well as AP biology high school classes.