An exciting night in Las Vegas results in the death of three people , one male dead in an alien suit, one male found dead in a bathtub, and one female found dead. The CSIs suspect that the killer is one of two suspicious men at the scene of the crime. However, the case becomes more complex when the team discovers that one of the dead males was holding a Polaroid of another dead male. Meanwhile, Greg, 's replacement arrives at the lab.

After a heavy downpour in Las Vegas, a body washes up in one of the city, 's storm drains. When the team arrives to examine the body, they come across bones from another murder. Now, the team must determine the cause of death for the first body and look into the origins of the bones.

The CSIs race against the clock to find a young girl who was kidnapped from a convenience store parking lot. Will the CSIs be able to find her before it, 's too late?

A woman turns up dead in her hotel suite from what appears to be caused by the ebola virus. When another woman is found dead with similar symptoms, Catherine and Nick are sent to the scenes to investigate. Meanwhile, Sara and Greg team up with Grissom to find the cause of death of a home owner after his house was tented for an insect infestation.

Sara and Grissom investigate when a woman is found dead after a swap party in which the married couples in the neighborhood get together and swap spouses. The evidence they collect shows that the victim had several partners during the night which leads them to a neighbor, 's back yard. Meanwhile, Warrick and Nick investigate the murder of a video arcade landlord and find that there, 's more to the crime than they originally thought. Meanwhile, Catherine tries to get a promotion in order to become part of the day shift.

A killer from the past returns, this time with equally deadly results. Now, the CSIs must race against the clock to find the killer before he strikes again. Meanwhile, Grissom begins to stress out when he starts to think that the killer is outsmarting him.

A 17 year-old is murdered in a casino penthouse and Grissom heads out to investigate the scene. He is joined by Sophia Curtis, a day-shift member, who aids him in his research. Later, the entire CSI team is brought onto the case when Grissom and Sophia discover that a kidnapping occurred along with the murder.

A woman driving erratically is pulled over by police. Two miles up the road from where she was stopped, she is found dead in her car. During the autopsy, Dr. Robbins determines that all is not as it seems , the woman is actually not a woman. This revelation leads the team into the world of sex changes and transgenders in order to find the killer.

While testifying in the murder trial of a restaurant owner, Grissom is presented with new evidence that leads the team to reopen the case. The reopening of the case causes Eckley to closely examine Grissom and his team, 's effectiveness, and the results of his examination leads to an unprecedented change in the both the team and the series.

Grissom and his newly formed team investigate when a five year old boy dies from starvation. Their investigation leads them to discover that the boy has siblings that may be nearing the same fate as their brother. Meanwhile, Catherine and her team work to find the man who killed a prisoner during a cell fight.

A Sherlock Holms enthusiast is murdered in his perfectly recreated Victorian Era Baker Street study. At first the team believes that the death was a suicide, but after reexamination of the scene and of the evidence, Grissom determines that other factors were involved in the man, 's murder. Meanwhile, Nick and Warrick look into a car accident in which the driver went over an embankment out in the desert.

A baby rattlesnake is found in the throat of a decapitated head. In order to catch the killer, the CSIs put themselves into the world of narcocorrido, a Mexican musical lifestyle that idolizes violent acts and brutality. Meanwhile, Sofia and Greg investigate the death of a woman found dead in the front seat of a handicapped van at a casino. They soon discover that the shooter had to have been confined to a wheelchair, narrowing the search.

Two female corpses are found in a new construction site, leading the CSIs to the world of Russian mail-order brides and the torture the women go through in order to earn citizenship through marriage. Meanwhile, Sara is lectured by Ecklie after she makes an inappropriate comment, leading her to confide in Grissom a family secret she, 's tried to hide from the rest of the team.

When a Kodiak bear is found dead with its gall bladder removed, and the body of a murdered hunter nearby, the CSIs determine that another suspect was involved in both murders. Meanwhile, a young mother is found dead after a heavy night of partying out in the town. After some investigation, it seems that her husband isn, 't as innocent as he looks.

A casino owner is found dead and naked in his driveway and both CSI teams get together to find out who killed the man. After thorough investigation of the evidence, the CSIs discover an adult nursery hidden in the man, 's house. This discovery leads them into the world of infantilism: men who get pleasure from wearing diapers and being treated as an infant.

Grissom and his team are sent to an APAPSP convention, Association to Promote Acceptance of Plus-Sized People, to search for a killer. The evidence the collect shows that the victim died from asphyxia due to a large object stuck in his chest. Meanwhile, Catherine and her team are thrust into the world of high-stakes gambling when a man is found dead in the Vegas outskirts with a large amount of money and betting slips on him.

A serial killer strikes again in Las Vegas and the CSIs are able to dig up evidence from a past slaying in hopes that their new technology will help them find the killer. The fingerprints they are able to recover link them to Jesse Acheson, who quickly becomes their number one suspect. Meanwhile, a teenaged boy is found dead in his bedroom, and though his brother confessed to the murder, the evidence suggests otherwise.

Grissom uncovers an unlikely connection between a suicide of a woman in the nearby Vegas wilderness and the murders of an entire family in the Las Vegas suburbs. The evidence is able to piece together an unfaithful spouse and the deadly results of one woman, 's frantic need to get pregnant.

Catherine and Warrick investigate the death of a model who works at auto conventions after she is found murdered on a camper display. Nick looks into the death of a boy found beaten and burned to death on a bus bench near a strip mall. Elsewhere, a car accident leads Grissom to suspect that the driver intentionally hit his victim, while Greg and Sara examine the death of a body builder who died when a toxic mold ate him alive from the inside out.

Capt. Brass travels to Los Angeles to ask Captain Annie Kramer, a former colleague, for help when his daughter Ellie, whom he is not on good terms with, calls him for help after her friend goes missing. When the friend is found dead, Brass asks Warrick, who is also in Los Angeles for a CSI convention, to help him and Capt. Kramer hunt down the killer..

Sara finds semen on Robbie's sheets and questions Dr. Dino about it. We learn that Robbie was chemically castrated and therefore couldn't have been his. The CSIs decide to swab all of the inmates and the workers as well. At the morgue, Dr. Robbins tells Grissom that Robbie died of asphyxiation, not the blunt force trauma, which occurred post mortem.

At a bar after a tough day on the job, Catherine has a romantic encounter with a stranger, Adam Novak. When a woman at the same bar turns up dead, Adam becomes the investigation, 's number one suspect. Meanwhile, Catherine and Grissom clash after Catherine fails to tell him her connection to the suspect, while Mia deals with lab problems when the evidence becomes cross-contaminated.

When a college basketball star doesn, 't show up for the big game, one of his fellow dorm residents ends up finding the player dead in a sleeping bag with a girl in his dorm room. As Sara and Greg investigate the scene, all of the evidence leads them to dead end after dead end. Meanwhile, Catherine and her crew investigate when a body is found in what seems to be a crop circle , with no footprints leading to or away from the body.

Nick is kidnapped by a man with a grudge against the CSIs. When he awakens, he finds himself trapped in a coffin with a loaded handgun and a message telling him that he better kill himself because he, 's going to die anyway. Attached to the coffin is a webcam that tapes Nick, 's every move and sends the image back to the CSI lab where his co-workers slowly watch him suffocate. In a race against the clock, the two CSI teams combine back into one team, and under Grissom, the team works to find Nick. They try to hack into the webcam, but much to their horror, the picture is replaced by a countdown and a message telling them to bring a ransom to a warehouse. Grissom takes the money to the location and comes face to face with Nick, 's kidnapper. However, the kidnapper has an explosive plan that may lead to the death of Grissom and of Nick.

Grissom delivers the ransom money to the kidnapper, but the kidnapper blows himself up, leaving no clues as to where Nick is buried. As the clock slowly ticks away, the CSIs must rush to find Nick who is buried underground and slowly sufficating.