Nick, just back on the job, and Sara, distracted by her affair with paramedic Hank Peddigrew, discover progressively that a woman's apparent suicide was murder and her DNA proves she switched identity. Actually it's John Damon's wife, who left him and two young children nearly five years ago. A severed hand stuck in an industrial meat-grinder is traced to Les Dutton's restaurant, where chef Davidoff is missing, actually minced. Bloody staff customs and rivalry complicate Grissom's search for the culprit(s).
An eye is recovered from the beak of a raven. Catherine, Sara, and Nick attempts to find the rest of the body and discover the deceased at the Las Vegas garbage dump. They bring the body, along with items found around it, back to the lab hoping to find who the woman was. Dr. Robbins and David begin a routine autopsy only to realize that the man isn't yet dead. They revive him but he later die in the hospital. Grissom and Warrick investigate the cause of his suspicious death.
A little girl dies in her bed when her house is bombarded with bullets from an automatic gun. Her father and brother are unharmed. Warrick knows the family and lets his emotions rule his objectivity by immediately assuming a suspect to be guilty. This leads to a tragic conclusion for the victim's father and the suspect. Nick works on the case of a dead computer geek in a sealed room with only one exit. His three employees who were working on the other side of the door are all suspects.
There is a 'peeping Tom' on the loose in Las Vegas. He has just committed his first breaking-and-entering which means that he is going to commit more serious crimes any time soon. This fear becomes true when he rapes a young woman. The team works against time before this criminal strikes again. Sara, working solo, re-opens a case involving an assistant DA's husband's death. Three years ago, they were shot in their own home. The bullet got stuck in her throat and she is finally having it removed. The bullet is the only evidence Sara has to find the truth.
Two male prostitutes are found dead, one in a night club and the other in his own home. They both worked for Lady Heather so Gil Grissom and Jim Brass pay another visit to her house. Catherine, while processing the house of the second victim, receives a phone call from her daughter Lindsay who is stuck in her dad's sinking car alone. Things get more complicated when Lindsay's father is later found dead from a bullet wound. Sara is given the case.
The police pursues a car driving recklessly before stopping. The driver, who has a wooden stake sticking out of his head, stumbles out before falling down dead. This site attracts quite a crowd before the coroner arrives and authorizes the body to be moved. Catherine and Warrick works on a kidnapping of Isaiah, the son of a very famous basketball player. There was a ransom note left at the hotel lobby asking for $5 million.
An elderly lady drives her car recklessly into a café for no apparent reason. Meanwhile, a wife dies of carbon monoxide poisoning while her husband does not even though he was sleeping right next to her.
A really badly decomposed body of a man is found in a chemical waste barrel. The markings on the barrel indicates that it came from a warehouse, now used as an arena for specially-built remote-controlled robots to destroy each other.
Jim Brass asks Sara and Nick to re-investigate a case which was ruled as an accidental drowning when he sees how happy the once-grieving husband is with a new date and sports car. Meanwhile, Catherine and Grissom works to solve a case of a very famous comedian who fell during his act and died.
A horse stomps her trainer to death aboard a luxurious personal jet. The horse is then personally cared for by a vet in quarantine upon landing. Things begin to look much more suspicious and complex when the horse suddenly dies and the vet disappears. Another case involves the suicide of two teenagers in the middle of the desert.
A woman dies at a high school football field. She has been associated with a recently released prisoner. Greg's DNA lab explodes and evidence is destroyed in the fire. Warrick and Catherine are assigned to investigate the cause of the explosion.
A bank robbery results to the death of Detective Lockwood. No money was stolen. The only missing thing is one safety deposit box registered to a friend of Sam Braun. Catherine Willows decides to confront Sam about the incident which ultimately leads to the discovery that she is his daughter. Grissom finally decides to get surgery to correct his hearing.
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.