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

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.

Catherine's friend Laura's mogul husband Mark has a lot to hide behind his successful international corporation, and he's hired a crack team of assassins to carry out the murders of anyone who might be aware of what he's doing, and that includes Laura's lawyer and Laura herself.

A casino employee is beaten and raped on her way home from work, but she survives and identifies her attacker. Unfortunately, a DNA test sets him free and Grissom must wrestle with whether evidence can ever lie. Later, Grissom comes to the rescue of a coworker who ends up on the other side of the law

Nick takes the lead on a case where in the house a family of four, three pools of blood are found. Nick thinks that the little girl may still be alive, but Sara is doubtful, thinking that Nick's recent near-death experience is affecting his judgement.

Grissom, Sara and Warrick are called on to investigate an abandoned, blood-splattered apartment and Nick and Catherine must examine a dead scuba diver lodged in a tree.

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.

Catherine comforts Warrick when he is accused of murdering a famous Vegas gangster and even he is uncertain of his guilt or innocence.

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.

Catherine revisits one of the very first cases she worked as a CSI when the convicted felon in the murder claims the verdict was based on faulty evidence.

When Nick, Greg and Hodges take Henry to celebrate his birthday at a biker bar, they uncover a double homicide and find several suspects still at the bar who may be the murderers.

Jane Galloway lives in fear. Her doors are triple-locked. Every shade is drawn. The bathroom window is nailed shut. An alarm system is activated. Who killed Jane, and how could the murderer have possibly entered, and left, the house?

Grissom is confronted with new evidence while on the stand of a murder trial of a restaurant owner. This development requires the reopening of the case and Eckley initiates an inquiry into Grissom and his team. The results of the inquiry lead to dramatic changes of the CSI team and the series.

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.

The CSI's are called out to investigate the disappearance of a boy whose father died four years ago. Soon a couple is arrested at a convenience store with a boy matching the description of the missing kid. The only problem is they both claim it is their son. Both parents have exactly the same picture of the boy, with a scar on exactly the same place on his face. They hope a DNA-test could confirm who the real parents are, but when this information comes to light, it lead to another bizarre twist, possibly murder.

A wealthy defense attorney is killed at her son’s wedding but Nick’s car, containing all the collected evidence is stolen and the case is compromised. After discovering new evidence, the team suspects that someone from the wedding party may be responsible for the murder.

While investigating an elderly woman's murder, Grissom receives a miniature crime scene replica; Greg attends a hearing to ascertain his culpability in a teenager's accidental death.

Identical twins are found murdered on the same night. The CSI’s investigate the two separate murders only to find a twist in the investigation find that leads them in another new direction.

Once he unseals a package sent to him through the mail, Grissom is floored when he finds a miniature crime scene inside. The finding is entirely more perplexing since the successive killer accountable for earlier related miniature crimes is now deceased. Grissom plows to examine the miniature and discover the actual location, when the investigation makes it clear the murder showed has yet to happen, but is probably going to happen soon.

As the CSI's continue their search for and discover the identity of the "Miniature Killer", Grissom and Sara's relationship gets exposed to the rest of the team as she goes missing during the investigation. The "Miniature Killer" is finally captured, but not before a member of CSI becomes the killer's final victim.

Three new murders related to three unsolved (or incorrectly solved) crimes from the past come back to haunt the CSIs.

The team is investigating the ongoing murders by a signature killer. The killer has some knowledge of forensics and has left little evidence behind. With the investigation somewhat stalled, the sheriff invites the FBI to join the case. This makes Grissom angry and it only gets worse when Sara offers to bait the killer.

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.

Greg, for his final proficiency, has to determine how the Sherlock Holmes of a Sherlock Holmes club was killed. Nick and Warrick try to determine how the driver of jeep was killed when the car ran off the road. They have to do this under budget while Catherine is watched by Ecklie.