This is an ethnographic study of a shooting that was labeled a drive-by and that resulted in the death of a fifteen-year-old boy. This homicide is seen as an unexpected event that in turn is used as an investigative tool to enhance data collected through observation and in-depth interview methods. I suggest that behaviors revealed by unexpected events can form the basis for theoretical and methodological concepts useful for the study of minority injecting drug users and other hidden populations at high risk to HIV infection and substance abuse.