Grissom is called to a murder of a 17-year-old in a casino penthouse. Sophia Curtis (Louise Lombard) joins him in his research, she normally works in the day-shift. The entire team gets involved when its discovered that a kiddnapping took place along with the murder.

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.

Grissom and his team investigate the starving death of a five year old boy. They discover the boy has siblings who are in danger too. Catherine and her team determine who killed a prisoner in a holding cell brawl.

The swing shift has a busy time. Warrick looks into the murder of man by someone who apparently needs a wheelchair. Nick looks into the murder of woman in the subculture of the narcocorrido, songs about drug murders. The night shift is slow and lends help to Catherine's team.

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.

When a major Las Vegas player is found dead, Ecklie orders both teams to investigate the case. The man who had secrets on everyone in Vegas had a very big one of his own.

Grissom, Sara, and Nick investigate a wildfire that killed one man and badly burned a woman. Catherine, Nick, and Warrick get the case of a family of three murdered in their home.

Grissom and Sara investigate the murder of a mental-hospital patient and quickly narrow down the suspects to a handful of other patients and staff members.

The two forensic teams come back together under the leadership of Grissom and Catherine just in time to tackle three separate investigations: a murdered couple found in bed in a suspicious trailer explosion; a beautiful stripper discovered dead and dumped in the worst part of town; and two bodies found baked and decomposed after spending five days in the trunk of a car exposed to the hot Vegas sun, forcing the CSIs to ""wrap"" up the evidence and bring it back to the lab for further analysis.

An up-and-coming movie star is found dead in his hotel room after a night of partying with his groupies.

The CSIs come across an abandoned military compound being used by a small cult. The CSIs grow suspicious when they see that a mass suicide has taken place, but only 11 of the 12 beds are occupied.

A 28 year-old single mother is found dead. Initially, it's believed to be a suicide, but Catherine determines she was murdered. Also, Ecklie summons Grissom to refute the testimony of an entomologist in a murder trial.

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.

Catherine and Brass investigate the case in which a man is found dead in a dumpster. It soon turns out the man had a serious food problem. The trail of his death soon leads to a hotdog-eating contest.Meanwhile, Nick and Sara investigate a not-so-amicable divorce with a bizarre twist. So bizarre it eventually lead to murder when both are found dead and it looks like the dog killed one of them.

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.

The CSI team investigates the murder of a man suffering from a congenital hypertrichosis, causing him to grow excessive body hair. Elements of the case suggest a connection with a belief in werewolves. The case leads to the victim's sister, who suffers from the same disease. Because of her condition, she'd been hiding from the world, but it turns out that she's hiding facts that are vital to solving the case.

The CSIs investigate the stabbing of a motocross racer who was about to leave town with a young woman he had been living with. Also, Nick comes closer to finding the truth about his kidnapping.

The CSIs crash an elegant party for the city's crème of the crème to discover who killed a young man. The case gets a bit more personal for Catherine when her father, Sam Braun, is one of the suspects.

The CSIs must investigate when a party girl is injured and killed in a traffic accident.

The investigation into a body found in a chimney leads the CSIs to re-open an investigation of an unsolved homicide of a female teenager named Caroline Fitzgibbons.

The CSIs become the focus of a reality TV series, which follows them while they investigate a serial rapist, who recently gained access to a woman's apartment by posing as a fireman. Also, Warrick's work on the late-shift is causing problems with his marriage to Tina.

When a student is arrested and tried for the murder of a popular high-school girl, the suspect's 12-year-old sister confesses to the crime. This results in the judge giving the prosecution 72 hours to re-examine the evidence before the jury delivers its verdict.

The team investigates the death of a psychic who "saw" her own death while performing a reading for two other women. Greg reveals a family secret to Grissom but Grissom believes that science will be what solves the case.

The CSI team is lead into the rap music world as they investigate the murders of three rival teen rappers.

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.

In the season finale, the CSIs wait by the bedside of one of their own when he's shot in the line of duty. One CSI faces a hard choice by having the power of attorney over their injured friend and colleague. Meanwhile, the team also investigates the strange way of life of one man when he is found decapitated by a train.

In part one of this two-part seventh season opener Grissom and Catherine handle the case of a women's dead body found at Cirque du Soleil by a performer. Meanwhile, an investor at one of Sam Braun's new casinos is shot to death during a party on the rooftop. Catherine's life is in jeopardy after visiting a nightclub with Nick. Grissom finds a miniature replica of a crime scene that he is investigating.

In the second part of this two-parter Grissom investigates the murder of an aging rockstar who is found dead in his kitchen with an exact replica of the crime scene on the counter next to him. Meanwhile, Catherine probes her own abduction and learns that someone may be targeting her family.

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.

Three tourists are beat up, badly. One is dead, Alfonzo. Jessica is badly beaten but is still alive. Stanley, the last tourist is saved by Greg who ends up severely hurt in turn and ends up hospitalized after having to make a life altering decision.

Grissom and Sara may be secret lovers, but they still find ways to surprise each other like when their religious beliefs surface when two nuns find a body of a woman crucified on a makeshift cross. The woman was found in a church where the priest may be a man of sin instead of a man of God.

Grissom attempts to get a confession from a neighborhood pedophile by having him help in locating two missing boys. The sex offender is the main suspect. The investigation is more complex than the team ever thought it would be.

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.

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.

Grissom investigates when a worker at a poultry processing plant is found dead in a stun bath used to electrocute chickens before they are slaughtered. Nearby, a miniature replica of the crime scene is discovered. It's eerily similar to two other replicas left at scenes of homicides. Also, a man and a dead woman are found stuck in cement at a construction site; and an elderly Russian woman is discovered dead in her apartment with her head in a gas stove, but Warrick thinks she was murdered.

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.

The team has a hard time trying to understand Michael who has become a team member since Grissom’s teaching hiatus. They investigate the murder of an unidentified girl who may have been killed by a serial killer who has been killing since the early 1970’s.

At Keppler's request Catherine uses a different approach to catch the killer, and in doing so she deceives the rest of the CSI team. The team soon discovers that something is amiss in Catherine’s investigation.

Nick and Keppler investigate the bizarre world of the black market sales of body parts after they find a body that has been burned and the organs removed. The rest of the CSI team investigates the death of rich woman who was killed in her own home.

Grissom returns from his sabbatical; Keppler is put into a compromising position when the bodies of a Trenton police officer and a hooker are found in a hotel room. The man who found them is a retired New Jersey cop and close friend to Keppler, who doesn't reveal their relationship.

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.

Grissom and his team are discouraged when they find a pool of blood as they begin investigating the disappearance of a high school basketball star and his cheerleader girlfriend.Grissom's quip that the young lovers may have run off to Mexico is soon quashed by the discovery of drops of blood by Ryan's vacant parking spot at the school. After finding a letterman jacket and cheerleading sweater in the field house and a pool of Ryan's blood nearby, the team tries to determine what went awry.

The terrified eyes and cryptic words of a murder victim haunt Sara while she processes the house where several showgirls were killed.

After a man is killed in his limousine, Greg finds that the murder victim has ties to the man he had to kill in self-defense. The team finds that the brother is involved in this investigation and has to deal with him and his hostile mother.

The CSI labrats take center stage to discuss the case of the Miniature Killer.

When a has-been boxer is killed, the CSIs must establish which of several life-threatening acts actually killed him.

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 investigates when a sadistic client tries to murder Lady Heather (Melinda Clarke), who makes the probe more difficult when she refuses to name her attacker. Also, Grissom's reunion with Lady Heather makes Sara uneasy.

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.

With time, the weather, and the desert against them, the CSI team must work together to find Sara before she dies from the miniature killer's attack.

Following his escape, Nate Haskell, the notorious "Dick & Jane" killer, resurfaces when he e-mails a disturbing video to the father of one of his brides, threatening to take her life.