When the class clown at the local high school is found murdered, the CSI team is called to investigate, while Nick and Sara respond to the crime scene of a decomposed body found in a bag.

Catherine is ordered by a kidnapper to accompany a man who is to deliver $1 million in ransom to him or else he will kill the man's mistress.

Catherine and Nick become absorbed in the dangerous world of street racing after one of the illegal sport's hotshot drivers is found dead out in the desert at an abandoned airstrip. Back in town, Grissom and his crew probe the sudden death of a renowned poker player who suffered a violent convulsion in the middle of a high-stakes game with three others. It looks like natural causes, at first, but Grissom suspects foul play.

Grissom and his crew are called in to investigate the death of a young woman found in the hotel room of popular actor Tom Haviland. Haviland admits that he slept with her, but denies killing her. Grissom believes otherwise, however, after finding blood evidence on the celebrity. Then things get personal when Haviland's lawyer hires Grissom's former mentor, Philip Gerard, to find mistakes in the forensic part of the case. And, unfortunately for Grissom, Gerard finds plenty of errors to exploit.

A middleweight boxing champ dies in the ring after taking a brutal beating from his nemesis, but Grissom finds evidence that points to murder. Outside, in a nearby parking lot, Catherine works a crime scene where a Los Angeles gang member was gunned down, apparently by a rival gang. Also, Nick investigates a jewelry-store robbery.

Grissom and Catherine investigate the grisly meat grinder murder at a slaughterhouse. Warrick and Sara look into the apparent suicide of a troubled young woman.

An elderly woman crashes her car into a crowded restaurant. One of the patrons is Sara's paramedic boyfriend. Grissom and Nick investigate the possible carbon monoxide murder of a woman in her home.