Catherine, Nick and Sara looking into a body found in the mountains that appears to have been dead for months. This leads the trio into the world of the world of robots and "robot wars", where robots are designed as "gladiators", to fight in an arena until one is incapacitated. Elsewhere, Warrick and Grissom investigate the body of a man in an alley, but their investigation is made difficult when the medical examiner “loses” the body for 11 days. Greg is called on to help the investigation by going undercover when a connection to an illicit gambling operation is found.