Responding appropriately to the smell of food or the scent of danger can mean life or death to a fruit fly, and brain circuits are in place to make sure the fly gets it right. A research team has identified an important component in these circuits: the point at which incoming sensory information begins to be transformed into a signal that instructs a fly's response. The cells, MBONs, distill nuanced information about an odor into clear instructions: approach or flee.