This clicker case study is based on the true story of Ella Buss, a young girl infected with the bacterium, Borrelia burgdorferi, the causative agent of Lyme disease. Ella did not show the early signs of the disease, including the tell-tale bullseye rash, which raises the question of how infection leads to disease. With respect to Lyme disease pathology, the evidence explored in this case study suggests that one should not focus too narrowly on the destruction of neurons (“trees”), but also consider the broader “forest” interactions with neighboring cells, the microglia. To explore these interactions, students learn how invisible molecular molecules (“markers”) can be labeled so that researchers can identify and visualize the health and activity of cells. Designed for a junior-level cell biology class, the case can be adjusted to match the learning objectives of high-school students. The case can be used as a stand-alone activity or as a follow-up to “Taking the Time to Understand the Uptick in Lyme” (Yang, 2020), another case study based on Ella’s story with an emphasis on ecology.