After a tough day at the work, Catherine invites Warrick and Nick to drink in a bar. She goes alone and meets Adam Novak, a stranger that fives his phone number in a matchbook. He offers to go to her car with her, they kiss each other and Adam turns brutal when she does not want to have sex with him. She hits her head on the door of the car and goes home. While sleeping, Catherine gets a call from Grissom and heads to the crime scene, where Alice Granger is found dead with a shot in her head. When Det. Vartann find her car nearby the bar where Catherine was, she goes with him to investigate. When she finds a matchbook in the belongings of Alice with a phone number, she heads home to find Adam's matchbook, but it has been thrown in the garbage. Their further investigation indicates that her ex-boyfriend, Jeff Simon, might be the killer, but he had a strong alibi. Catherine tries to tell to Grissom about her possible involvement in the case, but he does not give much attention to her. But when a second victim is found with the same M.O., they realize that the killer might be the same.

Someone tries to kill a diva called Lois O'Neill, who was related to the mafia years ago, and a waiter is killed instead. The CSI investigates the case, but more than ever, nothing is what it seems.

The hanging death of a possible hermaphroditic male is connected to a tainted water supply, while the day crew investigates 40-year-old skeletal remains found at the site of a recently-imploded casino.

The skeletal remains of three people are found in the desert. Initially beetle evidence implies they had been dead at least a week but other factors contradict that. They bodies were identified as a lawyer, that Catherine had a connection with, and his two employees. Catherine had recommended the lawyer to a friend, who was trying to escape her dangerous husband. After analysis the beetles appear to be genetically altered. Catherine fears her friend could be dead until she makes contact with a location.