About the show
Cold Case is a police drama based around Lilly Rush, the only woman detective in the Philadelphia Homicide Division. One day she is approached by the witness to a crime that happened thirty years ago. She is driven to solve the case and when asked if she'd like to be put back in regular rotation., she states she'd rather continue working "cold ones", the term used by the detectives for unsolved cases. Lilly and rest of the squad strive to give victims and their families justice after years of it being denied.
Usually, each episode would focus on a single investigation. All cases involved murders committed in Philadelphia, although investigations occasionally required travel outside the city. Cases were also spread out over much of the previous century, with some as recent as a year or two old and others dating back to the 1930s. Generally, an investigation would begin when the police received a new lead, or "new direction", on a case. This might be the discovery of a body or a critical piece of evidence such as a murder weapon. One episode, for example, began when a gun received in a gun buyback program was linked to a murder through ballistic evidence. In some cases the lack of a body meant that it was originally unclear is a crime had even occurred, with people instead believing that the victim had merely left town.
Over the course of the episode, the detectives would interview witnesses associated with the crime and piece together the story of what led the victim to their death. These interviews were accompanied by flashback sequences to the time of the murder which dramatized the testimony. Witness testimony, even from people who would later be revealed as the killer, was almost never false. At most the guilty party would lie by omission, leaving out critical details, or stopping their narrative before they implicated themselves. The witness testimony was also generally presented in chronological order so that it formed a cohesive linear story for the audience.
At the end of the episode, the police would be shown arresting the killer and walking them into custody as the spirit of the victim looked on appreciatively. This would be accompanied by the playing of a song meant to symbolize the period in which the killing took place.
Through the flashbacks, the show examined many issues related to 20th century history, including: racism, homophobia, sexism, abortion, and police brutality.