When a teenage boy commits suicide after firing on a doctor and hitting an innocent party, Fontana and Green investigate why he was after the doctor to begin with and learn that Jeremy Miller's younger sister had recently died of AIDS. Throughout the course of the investigation, detectives are led to Dr. Andrew Copelan, the doctor in charge of Emily Miller's care, who had been giving her an experimental AIDS drug not yet approved for usage on humans, ostensibly to find a cure for his own AIDS.