Melanoma is a somewhat unusual cancer — one that blooms before our very eyes, often on sun-exposed skin, and can quickly become deadly as it turns our own skin against us and spreads to other organs. Fortunately, when caught early, melanoma can often be cured by simple surgery, and there are now better treatments for advanced cases, including immunotherapies that prime a patient’s immune system to fight off the cancer. However, much remains unknown about melanoma, including the details of how it develops in the earliest stages, and how to best identify and treat the most dangerous early cases. Spatial maps of melanoma reveal how individual cells interact as cancer progresses.