When the lead suspects in Grissom's serial killer case are murdered, Grissom suspects an inside job. Grissom and Brass are at odds when Grissom suggests it was a cop. Catherine and Sara investigate what happened to a college football fan when his bloated body is found in a bathtub.

A teenager is found murdered on a construction site. Grissom, Sarah, and Warrick follow the lead of blood on a hammer. Nick, with an assist from Catherine, tries to find how a woman was killed by a gunshot on her lawn when no one nearby had a gun.

A roller coaster runs off track leaving 6 people dead. The CSI team must uncover whether this was an accident, or foul play. Warrick and Catherine try to find the killer of a 13 year old girl.

When eight bodies are found in what appears to be a meteor site in the middle of the desert, CSI Finlay recognizes one of the casualties, prompting her to revisit her past.

When a woman is found dead in Mexico and a murdered couple is discovered in a driveway, evidence from one investigation could help the other.