This episode is well-remembered for the lighthearted chemistry between Grissom and Catherine. The scene where Grissom tries to "motivate" Catherine while she’s running by playing "Chariots of Fire" —only for her to call it a "sedative"—is a fan favorite.
Grissom and Catherine investigate the death of a runner (a fellow cop) who collapsed during the race after ingesting a lethal combination of seemingly harmless substances. [S4E20] Dead Ringer
" Dead Ringer " is the 20th episode of 's fourth season. Originally aired on April 29, 2004, it is generally considered a solid, high-stakes procedural that cleverly uses a massive law enforcement gathering as its backdrop. Plot Overview " Dead Ringer " is the 20th episode of 's fourth season
The episode excels by making almost every suspect and victim a police officer. It explores the tension and "code of silence" that exists even when CSIs are trying to find justice for their own. It explores the tension and "code of silence"
Reviewers often praise the "hectic" energy of the episode, capturing the chaos of a city overrun by off-duty cops partying and competing.