Need to conduct multiple experiments on a single cell over time? Too bad. At the cellular level, we just have a wide-angle view, because the tools currently available to biologists show only whole cell populations at once. But much like people, individual cells behave differently, and each one can change the fate of many others. So Christopher Love, as a chemist-turned-immunologist, has developed a technique to zero in on an individual cell. His goal, he says, is to "take a picture of it, ask who it is." Spotting a cell's unique quirks over time could solve long-standing medical mysteries: how the immune system responds to HIV infection, what methods doctors should use to diagnose deadly allergies, and why drug production is so inconsistent, and thus so expensive.