Several couples are killed bloodily after a wild party night in the same luxury hotel with Cameron and Mandy Klinefeld, or rather one somehow forced to kill the spouse. Nick is pleased to bump into former college mate Kenny Richmond, who works there, until it seems buddy boy passed confidential information to the press, which could get Nick fired.
A grossly decomposed corpse in a bath tub is identified as frat student Daniel O'Hannissey. He was last seen in a bar, taking part in a brawl about team sports, but left apparently unhurt. Meanwhile, the serial couples killings investigation takes a sharp turn when both are murdered in their home, while the undercover police observation was diverted.
Fingerprints suggest a link between two home invasions, but it's hard to link either the victims or the logical suspects, who may all be innocent. The crucial survivor testimony proves the most tenacious problem. A toddler found and accidentally fired a murder weapon in the family's suburb garden. Its place is a mystery, being so overt and unrelated to the victim, a bounty-hunting has-been, until the team consults the sky.
During a week-log heat wave, corpses are found, mostly accidentally. A.D.A. Jeffrey Sinclair decides to 'make an example' of a workaholic father who forgot his baby-boy in his scorching-hot car with fatal result, but the team finds the couple lost a previous baby and may have murdered this one. Mark Young is missing since his teen date's fatal lake sports accident. A fat man on a crazy diet was electrocuted at home.
Robert Pitt was run over by a truck which hit a car. Pitt was wearing his sophisticated 'Rocky Raccoon' costume, for the PET convention in Vegas, so Grimssom goes there. Pitt was also lethally shot with a rare, powerful pistol. Nick investigates the fatal shooting of a man, left in an icy meat-locker, while security guard Petey was cuing up for burgers, and finds the case revolves around stolen ice-cream just past expiration date.
The sheriff of desolate town Jackpot calls in CSI for assistance after a severed head is found. The sheriff proves rather more cynical than helpful towards Grissom, unlike the veterinarian-coroner. The rest of the corpse is found buried to the shoulders alive, an Native American torture technique. Grissom triumphs over sabotage and works out the local reports and relevant secrets.
Because Warrick naively assumed simple uniformed cop Hal Watson would have arranged a search warrant, the crucial weapon in the rape and murder trial on a neighbor against Michael Fife is dismissed as evidence in court. A.D.A. Jeffrey Sinclair can only get a 24 hours delay to present new evidence to build the case again. Nick brilliantly smooths emotional waywardness from Sarah and Warrick. New clues expected to reconstruct the case against Fife actually indicate he's probably innocent. An alternative culprit must be found, starting from Fife's car where the bloody ...
Julie Waters, a dancer, has been missing for 6 days. A suspect, Howard Delhomme, calls the police and turns himself in. He refuses to talk to anyone but Catherine. Sarah and Nick want to work on this case because they see it as a career-making step. Grissom, to their anger and disappointment, hands the rein over to Catherine. Despite their initial antagonism, they all worked together to find the young girl.
Grissom, Catherine and Nick investigate a car bomb which resulted in the deaths of three people, one of whom was an air marshal who rented the car. Due to the imprecision of the detonator, the CSIs conclude that the target may not have been the air marshal, but the person who had previously rented the car. The man is a mystery himself, as he seems to be leading a double life. In town, Sara and Warrick work on the death of Amelia, the wife of Myles Reuben, a famous singer. His wife was found in her hotel's bathtub while Myles was performing downstairs.
Teenager Brian Haddick is found on a construction site, skull fatally smashed, with an employee's hammer. Grissom's team checks on the construction crew as well as Brian's school crowd, stumbling on abused love and dirty practices. Another victim was killed by a bullet which literally fell from the sky.
A juror dies during a trial in a heavily guarded safe house. A four-year-old case of a missing woman is reopened when the woman's sister gives the CSIs new evidence she withheld during the original investigation.
A nurse is found dead in her house by her friend, who's also a nurse. The victim died in her spacious bathroom, posed with her head facing the door. According to the friend, she was to have dinner with her new boyfriend, Dr. Michael Clark, who works at the same hospital. Processing the crime scene reveals very little evidence because the killer has thoroughly cleaned the place and used bleach to denature any DNA. Dr. Clark, initially a prime suspect, is later found, albeit in pieces, in garbage bins behind the house. The precision of various cuts suggests that medical...
Nothing is as it seems when the CSIs are called in to investigate an apparent death in a hotel pool by electrocution. It turns out that the body is a dummy. The real crime scene is inside the hotel when an antique Japanese sword is stolen from an exhibition. As this investigation proceeds, the detectives will find that there are more deceptions in play. Another case involves the death of a teenage girl who's into the vampire cult. All the blood in her body has been sucked out.
There's been a supermarket robbery with 5 deaths, one of whom is a police officer. Another police officer was at the scene and is being questioned when a bullet from his gun killed a civilian. The policeman insists that he shot another robber, but his body wasn't found in the crime scene.
Two masked men show up at a house and kill the husband and wife execution-style with two bullets at the back of the head. The man's body is then dragged from the fairly secluded driveway towards the street, a fact that greatly puzzles Gil Grissom. The couple lived at a very good and secured community with only two entrances, the main gate to the whole complex, and a personal back gate.
A man who works at a half-way house is found dead in an area filled with drug addicts and prostitutes at night. His belongings were stolen, form car to shoes. Another body is found wearing only his boxers with signs of a clown's make-up.
Parts of a body is found tied under a bus taking her fellow inmates to church. Catherine, Sara, and Nick have to retrieve various parts of her body along the road. Autopsy reveals that she was already dead by the time she was tied to the bus. Grissom works on a case of a man stabbed to death in an apartment.
A very large man is beaten to death by a smaller man with enormous strength. During interrogation, the suspect jumps on Grissom and is subdued by police officers in the room. He ends up dead, not from being beaten, but from cardiac arrest. The findings in his stuffed car, which includes a waitress uniform, leads Grissom to investigate the dead man's motel. The result shocks the team when a skeleton of a woman is found buried in his property.
A teenager dies from inhaling smoke during a fire before firemen could rescue her. The rest of her family, her mother, younger brother, and grandmother are safe. Catherine, Nick and Warrick works on the case which unveils an unexpected and shocking finding. Gil Grissom and Sara investigates the death of a man found in a hotel's bathroom. Autopsy reveals that he had swallowed 6 pieces of game tiles and had suffocated to death. The tiles lead the two detectives to an annual championship of Logos, a word game similar to Scrabble.
The team investigates the death of three police officers in a time when over 20,000 policemen gathered in Las Vegas for a marathon. One of the bodies, a male, is found by Grissom and Catherine during their run in the race a little off the route. Two others, a man and a woman, died from gunshot wounds in the man's hotel room.
Three crimes are explored in this episode. Firstly, an employee of an amusement park is found dead due to head injury, near a roller coaster accident where a car came off the tracks, leaving several passengers dead. Foul play is suspected. It is believed the murder and the roller coaster damage are linked. Also, a 13-year-old girl is found dead outside, again cause of death from a head injury.
The body of a young gambler is left at a neon graveyard. He died from two gunshots to the back of his head. Prior to his death, he won a lot of money from one of Sam Braun's casinos. This makes Grissom remove Catherine from the case.
A raped victim identifies her attacker from a line-up, after correctly giving the investigators his license plate number and physical description. While DNA is recovered, it indicates that the suspect is not guilty, as only 7 out of the 13 alleles matched. This suggests that the rapist is a relative. The suspect's brothers are all DNA-tested and none are a positive match. The resolution of this investigation is a shock to everyone due to the rarity of a genetic condition.