The CSI unit is closed after it's discovered that a body has been exposed to radiation. Horatio tracks down a lawyer who is also dying of radiation poisoning.
As the team tackles a case involving a dead doctor and black market organ transplants, Calleigh suffers smoke inhalation and falls into a coma.
When evidence suggests that a series of murders is linked to organized crime, Horatio and the team are led to a pair of film students.
The CSIs investigate the murder of a wealthy racehorse owner. As the case unravels, it seems that a Russian gangster could be involved.