Format
Each episode of Cold Case begins with a flashback scene informing viewers of the year in which it takes place. A set of characters are revealed in a seemingly mundane situation. The viewer is then shown the corpse of the victim as he or she was found. It is always one of the people introduced in the previous, seemingly innocent, scene.

The show then flashes to the present day. The detectives of the homicide division of the Philadelphia police department are told there is reason for further investigation of an old case gone cold, for one of several reasons: new evidence has come to light, the victim’s physical remains have been discovered, a witness has decided to come forward, etc. All or any of these cause the detectives to give the cold case a new look and begin researching the victim and interviewing their friends, acquaintances, and family.

The friends, family, co-workers, etc. who were introduced in the flashback at the beginning of the episode have aged (in one case, a six-year-old witness to the crime is interviewed by the detectives when she is 94). Gradually, the detectives gather enough evidence to determine the killer, who most of the time is then arrested.

At the end of each episode, the detectives mark the case solved, while an apparition of the murdered person(s) looks on.

The problems in the detectives' personal lives are also featured, though the main emphasis of every story is on the victim and the search for the killer. Most notably, Detective Lilly Rush grew up in a severely dysfunctional, poverty-stricken home with an alcoholic mother.

Cold Case is also notable for double-casting: it will cast a young actor for the flashback sequences and an older actor for the shots in the present, and cut back and forth between the two, to show how the character has aged. The episode "One Night" managed to triple-cast one character, showing him in the present day, when he committed his murder, and when he was a teenager. If the murder takes place within the recent past, i.e. one to five years earlier, the same actors are often used with subtle changes in appearance and with a few exceptions (i.e: infants to adolescents). If the murder takes place in the distant past, i.e. 15 years plus, different actors with a few exceptions are used (e.g. adult persons who are not likely to age significantly other than gray hairs and/or weight gain/loss).


Victims and end scenes
Typically once the murderer is revealed, their confession is depicted in one final flashback in which the murder is shown. The episode then ends with a montage (with no dialogue) of the killer(s) being arrested, as well as the fates of other characters from that era, showing all of them in their current appearance, but briefly flashing back to their younger selves, and finally Detective Lilly Rush or someone else close to the victim seeing a vision of the grateful-looking victim standing nearby, who then quickly vanishes (this aspect of the show is left up to viewer interpretation: depending on the viewer's perspective it could be Rush's imagination or it could be representative of the victims themselves). There have been numerous variations on this pattern however. In some cases the final vision is seen by another member of the team because of a connection to the victim. Other visions are seen by someone close to the victim. Some cases do not end with an arrest or vision at all. In the first season "Hitchiker" episode, the culprit sees the victim both as a teenager and as an adult, the only time this type of vision occurs. This latter because the victim is an infant or the former because the actual culprits are already deceased. The fifth season episode "Family 8108" had the rare distinction of ending with an original monologue instead of a song during the closing montage.


Notable Unlikeable Victims
Generally the majority of the victims are shown to be good people or truly innocent victims thus making the