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.

A woman is abducted from a supermarket. In the store, Grissom finds a bathroom stall door that claims five women have been killed. Warrick is caught in a casino on duty and is paired with a reluctant Sara. Their case is the apparent murder and robbery of a man who is found be his brother. Nick gets pulled in by his prostitute friend who gets in a scuffle with hotel security.

A bomb goes off in an office building killing one and injuring many more. The chief suspect is a security guard who left minutes before the explosion and has knowledge in bomb making. Nick helps his prostitute friend again. After giving in to his passion, she is found dead the next morning. Naturally, Nick is a suspect and to make it worse, Ecklie has the case.

Grissom and crew are called in after high roller Tony Braun, a known drug addict, is found dead in his house by a gardener. Since drug paraphernalia is discovered near his body and it is also determined that he had recently inhaled heroin, the cause of death is at first thought to be an overdose. But further examination of the corpse reveals that Braun had been restrained at some point with duct tape, leading Grissom to believe that the victim was forced to ingest lethal amounts of heroin and, perhaps, other drugs.

Grissom and Nick investigate the death of a book restorer while Catherine and Sara are called to the scene of a fatal train crash.

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 and his crew handle their highest profile case to date when the city's former chief of detectives is slain execution-style in his house following a wild party. Missing from the residence are the chief's trophy wife and their 7-year-old daughter. Catherine and Warrick follow the trail to Miami, and soon enlist the help of Horatio Caine.

Season Finale. The CSIs investigate when the body of an unidentified young woman is discovered stuffed in an overturned shopping cart near a freeway underpass. Her horribly disfigured and partially decomposed face is a nightmare of blood, scabs and scars, as if she'd been shoved into a fan. A huge circular hole dominates her left cheek. Someone not only wanted her dead, Grissom reasons, but ""they wanted her ugly."" Adding to the mystery are the cart's other contents: an expensive handbag, fashion magazines and a leather day planner with notes written in code.

Catherine and Nick become absorbed in the dangerous world of street racing after one of the illegal sport's hotshot drivers is found dead out in the desert at an abandoned airstrip. Back in town, Grissom and his crew probe the sudden death of a renowned poker player who suffered a violent convulsion in the middle of a high-stakes game with three others. It looks like natural causes, at first, but Grissom suspects foul play.

Fifteen years ago, Catherine helped put John Mathers on death row for the rape and murder of a coed at a nearby college. Her body was dumped in a trash bag, and two other girls found the same way were also linked to the suspect. As the episode opens, Mathers is about to be executed when he's granted a stay based on new DNA evidence. But while Catherine awaits the results of tests on hair samples found on the first victim, another girl at the same school is murdered... and discarded just like the first three - meaning the wrong man could be behind bars.

Distracted by an attractive passenger, an Indian taxi driver feels his cab strike something at a suburban intersection. When he gets out to check, he finds a teenage boy pinned beneath the left rear tire, apparently killed on impact. The cabbie jumps back into the taxi to call for help, but a mob of angry onlookers - all of them white - drags him out and beats him for the crime. When Grissom arrives on the scene, he discovers that the teen has been eviscerated and has stab wounds, but shows no signs of having been struck by the cab.

Grissom and Catherine investigate a movie-goer who was stabbed to death; the team comes to a forensic impasse while processing a teenager who died from a gunshot wound.

Things get personal for the CSIs in the top-rated series' third-season finale, which explores the intersection of the investigators' work and their personal lives. Three masked bandits steal a safe-deposit box from a Las Vegas bank in a daring daytime heist, during which Det. Lockwood is killed. Lockwood's death provides Grissom and his crew with added incentive to find the murderous culprits. But the case really hits home for Catherine when the evidence leads to casino owner Sam Braun, who is like a father to her. Also, Grissom's hearing gets progressively worse and he seeks out Dr. Robbins for help.

A severed head is shipped to Dr. Robbins from Jackpot, Nevada. Grissom goes to Jackpot to find the rest of the body and gets very little cooperation from the locals. Catherine gets an unexpected gift from her father.

A wild night in Las Vegas has the CSIs simultaneously investigating four fatalities. Greg Sanders' first day in the field has him assisting Grissom's investigation of a fatal nightclub shooting. Meanwhile, Catherine probes into the death of a stripper found dead in a hotel room, while Sara and Nick look into the strange case of an "alien" body found near Area 51.

Grissom and Sara investigate the murder of a woman after a swap party. The married couples in the neighborhood meet and switch partners. With the help of a crime scene cleaner, Nick and Warrick find there was more to their crime scene than they first thought. Catherine wants a promotion to day shift supervisor.

Grissom, Sofia, Sara and Greg investigate the disappearance of a woman coming home from a night out with a friend, her abandoned car found on the edge of a highway. Catherine, Warrick and Nick investigate the deaths of a hunter and his prey, a Kodiak bear.

Brass travels to Hollywood, California to try to track down his estranged daughter's friend, meanwhile trying to rekindle some kind of relationship with her.

The CSIs investigate a man's claim that his wife fell down a set of stairs in their home.

The team must investigate the death of a police officer who died during a shootout leaving hundreds of bullets on the crime scene. The case becomes complicated when it turns out that Sofia Curtis and Jim Brass were with the victims during the shootout. When it turns out the officer died from friendly fire, it is up to the team to find out who fired the fatal shot. Meanwhile, Sofia is wondering whether she fired the fatal shot or not. She decides to hide the fact that the officer stepped into her line of fire, afraid it will ruin her career.

The CSIs sift through the overwhelming evidence from a shootout with drug dealers in order to determine who is responsible for the death of a police officer killed during the incident.

Coming straight from the perspectives of five people: Donna, Rebecca, Jack, Lou and Ray. All with one thing in common. They’re all dead. Brass and Catherine get to handle the case of Donna, who’s a cop from San Francisco, moonlighting as a bodyguard. Warrick and Greg work the case of Rebecca, who’s a former supermodel who died while hiking with her new husband Gavin. Nick and Sofia handle the case of Jack, a returning veteran from Iraq, who was killed in front of his wife and baby daughter who he just met for the first time. Grissom and Sara take the case of Lou and Ray whose bodies were found in Lou’s garage.

The Cadillac of an infamous 1970’s mob boss turns up in a lake, even though he disappeared years ago. A photo of current murder victims also turns up in the car, so the team must determine whether this current murder spree is related to the missing gangster.

Catherine testifies in a murder trial in which a man is accused of murdering his own mother three years ago, but the suspect is found not guilty. Catherine, however, believes he did commit the crime and that he may also have killed two other people, so she sets out to find the other victims. Grissom prepares to leave on a four-week sabbatical.

Several suspects in a murder case are UFO-club members who believe shape-shifting aliens have been working to conquer the human race for centuries

Grissom and the team join forces with Jack Malone, an FBI Agent from New York to track a serial killer.

The crossover continues on Without A Trace S06E06 Where & Why (II).

Grissom and his team battle the flu when they are called upon by D.D.A. Klein to investigate the deaths of several key witnesses for a grand jury case against a dangerous Las Vegas gang.

A deer is illegally killed, and the person found with the body in the back of his truck apparently dressed it in a tutu. The man, who was completely drunk when arrested, was being interrogated by Nick and Brass, and suddently tries to escape and is pepper sprayed. Unfazed by the spray, officers then taser him and he bursts into flames and dies. Meanwhile an unbalanced woman wearing a tinfoil outfit at the front desk tries to warn people (including Nick) of an alien invasion. After observing the burning man, she later turns up dead with green-tinted blood. When other people turn up with the same problem, it's up to the team to figure out why. Meanwhile, an old couple dies, apparently in their sleep... but there is evidence the cases are related.

After Warrick is shot in a Las Vegas alley, the CSI team comes together to deal with the aftermath.

When the team discovers a connection between a new murder and a serial killer, Grissom secretly joins the class of a criminal pathologist (Laurence Fishburne) to help crack the case.

The CSI team is shocked and saddened when, after working with Dr. Raymond Langston (Fishburne) on the "Dick & Jane" murders, Grissom announces that his time as a CSI has come to an end and offers Langston a permanent position on the CSI team.

The son of a notorious killer is arrested on suspicion of murder, and the CSI team must overcome their natural prejudices against the boy's antecedents in order to track the true culprit.

The team investigates the cyber-related murder of a prominent casino owner's wife and receive help from the FBI's Cyber Crime Division.