The murder of a seemingly clean-cut young man has the CSIs delve into the erotic world of S&M. The victim, Ian Wallace, was tortured before he was killed and left by the side of a road. When the CSIs begin to look into details of the victim's life they find that this "frat boy" has a dark secret life involving sexual torture, and is a frequent visitor of an S&M night club. The victim's girlfriend Justine Stephani, who had been missing since the night of the murder, is the prime suspect until she is found run over and burnt to death.
As CSIs begin to piece together a forensic picture they find two new suspects - an S&M slave, Martin Devlin, and his young feisty female lawyer Kumar Sinclair who turns out to be the Dominant to both Devlin and the victim Wallace at the S&M club they all frequented. The evidence could not directly link either of the suspects to the crime and other clues lead investigators to believe that the killings were more random than originally thought. The mystery remains unsolved and will be picked up in a later episode. Grissom seeks out the assistance of a former Dominant Madam turned therapist, Lady Heather, but she thinks the case is a ploy and she pushes him for the real reason. After receiving a video "Dear John" letter, Grissom is having difficulty dealing with Sara's departure.