Gil Grissom is the supervisor of the graveyard shift of Las Vegas' elite crime scene investigators. Holly Gribbs, fresh out of the academy, joins the team. Jim Brass is head of the unit and is trying to scare Gribbs from CSI. Catherine Willows, mother of a young daughter, is the number two CSI on this shift. Warrick Brown and Nick Stokes are competing to solve their 100th case to earn a promotion to CSI 3. Grissom investigates a murder staged to look like a suicide with precious little evidence. Warrick and Catherine take the case of a drunk who breaks into the house where he had been staying and is shot to death. Nick talks to a man who picked up a woman who drugged and robbed him.

Grissom, Nick, and Sara search for a kidnapped woman and find more than they expected. Catherine and Warrick investigate the hit and run death of a little girl.

Catherine violates department protocol when she takes the case of a rape accusation against her ex-husband. Warrick and Sara search for the missing bullet that will either exonerate or indict a cop for murder. Grissom and Nick investigate when a female skeleton is found under a house buried in cement.

When a teenager and her sister are the sole survivors of the gruesome murder of four members of one family in a quiet suburban neighborhood, Grissom and his entire team investigate the crime. What initially looks like a bizarre cult murder becomes more disturbing when they discover the motive behind the massacre.

A woman is abducted from a mall parking garage. She's raped, beaten, shot and left for dead. Sara collects evidence from her and grows attached to her. Nick and Grissom analyze the crime scene. Catherine and Warrick are given boxes of evidence from a shooting that goes to trial in four days. The CSI who had the case has quit and they have to prove what happened. To make Catherine's life more complicated, Eddie has taken out a second mortgage without her knowledge.

Catherine is ordered by a kidnapper to accompany a man who is to deliver $1 million in ransom to him or else he will kill the man's mistress.

Grissom investigates the murder of two men that leads him to a new encounter with Lady Heather. Catherine is desperate to find out what lead to the near death of her daughter and why her ex, Eddie, disappeared.

A child is abducted. As the Amber Alert goes out, the entire team investigates in a race against time. Lindsay Willows is found hitchiking to the alarm of Catherine.

A man (Alan Rosenberg) whom Catherine flirted with at a bar reappears in her life as a suspect in a murder investigation.