Catherine, Nick, and Sara investigate a seemingly months old body found in the mountains. Discovery of the man's identity lead the team to the world of robot wars. Warrick and Grissom look into the case of a man found murdered in an alley. Complicating their efforts, the medical examiner ""lost"" the body for 11 days. Greg helps this case by doing some undercover work.

A mutilated female body is discovered tied to the undercarriage of a bus carrying prisoners from a women's correctional facility after a severed arm flies out from beneath the vehicle and strikes a car. Catherine leads the investigation and at first believes the woman was escaping, but the evidence increasingly points to murder. Back in town, Warrick probes the death of a gambler who was stabbed multiple times in his brother's kitchen.

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.