When the inmate Robbie Garson is found dead inside his room, Grissom, Sara and Capt. Brass investigate the murder. They learn that the inmates are criminally insane and rapists, and they get their DNA. When Sara finds semen on his bed, Dr. Valerie Dino tells Sara that Robbie had been chemically castrated and could not ejaculate. In the autopsy, Dr. Robbins finds that Robbie had various thing in his stomach and the cause of death was asphyxiation and his head trauma happened a couple of hours later. Sara and Grissom finds that the pharmacist Leon Cadera was stealing expensive drugs and giving simple medication to the inmates. When they identity the recovered semen belonging to Adam Trent, they change the line of their investigation.