There are 23 episodes each in seasons one to four. There are 25 episodes in Season five and 24 in season six. The seventh season has started airing in the United States and in the United Kingdom. The current number of aired episodes to date is 160.
When a man is found dead in a bathtub, an apparent case of suicide by a self-inflicted bullet wound to the chest, Gil Grissom suspects a homicide. Nick Stokes and Warrick Brown are competing to solve their 100th case and become a CSI level 3. Nick investigates the case of a man who was picked up by a hooker, drugged and robbed. Warrick and Catherine Willows take on the case of a man who has been shot to death after breaking into the house where he was staying. When Warrick breaks protocol to get a warrant in his case, he is forced to babysit new hire Holly Gribbs. After he leaves her alone at a crime scene to place a bet, she is shot.
After the Holly Gribbs shooting, Jim Brass is demoted to homicide and Grissom is made head of the graveyard shift. Catherine vows to solve Gribbs' murder and is irritated when Grissom brings in Sara Sidle from San Francisco to investigate Warrick's whereabouts the night Holly died. Grissom and Nick investigate the death of a 40 million dollar slot machine winner, who apparently committed suicide by jumping from a building.
Grissom, Nick and Sara find out that all is not what it seems when the wife of a rich man is abducted and buried alive in the desert. Meanwhile Catherine and Warrick investigate a hit and run that led to the death of a little girl.
A woman's severed leg found in Lake Mead leads Grissom and Catherine to uncover a case of adultery. Meanwhile Sara and Nick investigate a fraternity student's apparent suicide, but find out that the student's pledging has gone terribly wrong.
Grissom and Warrick investigate when a victim dies of fear in the desert, apparently from being chased. Meanwhile Catherine and Nick investigate the gruesome murder of a Catholic school dean. Sara investigates how the body of a woman who was buried the previous week ended up in a Dumpster.
Grissom and Nick investigate when the skeleton of a woman is found under a house, buried in cement. Meanwhile Catherine investigates a case in which her ex-husband Eddie is accused of rape. Warrick and Sara search for a missing bullet that could either exonerate or indict a cop for murder.
When four members of a family are brutally murdered, the two daughters are the sole survivors. At first Grissom and his team suspect a cult murder, but the evidence tells an even more disturbing story.
When another staged suicide takes place, Grissom realizes he is dealing with a serial killer who has a thorough knowledge of forensic science. Meanwhile Warrick and Nick investigate a tourist's car that fell off a cliff.
Grissom and his team investigate the death of a first class passenger on a flight to Las Vegas. Their investigation is a race against time, because after 12 hours the F.B.I. will take over. To make matters worse, the other first class passengers are very reluctant to cooperate, leading the team to consider that they had some involvement in their fellow passenger's death.
Grissom and Sara investigate when the body of a woman is found in the desert, covered with insects. Grissom uses entomological evidence to discover the time of death. Unfortunately their prime suspect - the husband - was out of town at that time, and to Sara's dismay it looks like he is getting away with murder. Meanwhile Warrick and Catherine try to find out who stole a painting. Nick deals with a missing persons case when a woman's car is found at a bus station.
When a woman is abducted from a supermarket, Grissom finds a text on a bathroom door that leads him to believe that five women have been murdered. Meanwhile Warrick and Sara have to put personal differences aside to investigate the apparent murder and robbery of a man who has been found by his brother. Nick has to come to the rescue his friend, Kristy Hopkins, again when she gets into a scuffle with a hotel security guard.
Grissom, Sara and Warrick try to clear a man accused of killing his wife and son in an arson fire. They discover Day Shift Supervisor Conrad Ecklie did some sloppy work. Meanwhile Catherine and Nick investigate the death of a teenage 'runner', who was shot at close range.
Grissom, Sara and Warrick investigate when a bomb goes off in a Vegas office building, killing a security guard. The prime suspect is the other security guard, who is over-helpful and also has the knowledge to make a bomb. After Nick spends the night with Kristy Hopkins, she is killed. With his DNA and fingerprints on the scene and Ecklie on the case, Nick's career is on the line.
When a single human bone is discovered in the desert, it's up to Grissom, Catherine and Nick to piece the skeleton together. Meanwhile Warrick and Sara investigate the death of a male stripper who died shortly after performing at a bachelorette party.
During a fundraiser at the home of Portia Richmond - a legendary showgirl - a dead woman is found floating in the pool. When Portia later disappears, suspicion falls on a young couple who 'house-sat' for her. The Sheriff puts pressure on Grissom as well, as Portia's case affects his election. Warrick looks into a mob hit in a glass elevator.
Sara gets emotionally involved when she, Grissom, and Nick investigate the case of a woman who is abducted from a parking garage, raped, and left for dead. Meanwhile Catherine and Warrick take over a case from one of the dayshift CSIs who has quit. The case involves a neighbor's dispute that led to murder. Not only has an important piece of evidence been lost, but the case goes to trial in four days.
Grissom, Nick and Catherine handle a case in which the fingerprints of a victim in an old kidnapping case turn up at the scene of a murder. Meanwhile Sara and Warrick investigate the case of a woman who was incinerated in her easy chair. Sara suspects it's a case of spontaneous human combustion.
A single witness at a rain-soaked scene of a double homicide tells the story of a carjacking gone wrong. After the car is found and becomes a new crime scene, the case becomes far more complicated. Meanwhile Catherine investigates the collapse of an apartment building that killed three senior citizens.
Grissom's team investigates the kidnapping of the infant child of a rich family. However, when the evidence shows that the family is hiding something, the case takes a darker turn.
Grissom, Sara and Warrick investigate a deaf man who was run over by a car. However, more investigation shows that he died before the car even struck him. The team's encounters with the dean of the deaf man's school reveals a secret about Grissom. Meanwhile, Catherine and Nick investigate an apparent mob hit that leaves five dead in a coffee shop.
Grissom, Nick, and Warrick investigate a jogger who was killed by a vicious dog in the park. The case gets complicated when they discover that the jogger's liver was surgically removed after he was killed. Meanwhile Sara and Catherine investigate the death of a six year old girl at a carnival ride, which gets Catherine emotionally involved.
On the day Grissom has to evaluate his team, Grissom and Catherine deal with a severed head that was found in the trunk of a stolen car. Sara and Nick investigate a headless body in the desert that appears to have fallen from the sky. Warrick investigates a murder in a juvenile detention center in which his young friend James is the only witness.
Grissom and his team investigate a series of murders by a signature killer. The killer has enough knowledge of forensic science to leave little evidence behind. When the investigation seems to be at a dead end, the Sheriff brings in the F.B.I., to Grissom's dismay. Grissom's anger only grows when they want to lure out the killer, with Sara as bait.
Tony Braun, the son of Las Vegas mogul Sam Braun, is found dead in his home, apparently the victim of a drug overdose. But as the scene lacks all evidence normally connected to an overdose, the team soon suspects murder.
The CSI team suspects foul play when university student Paige Rycoff vanishes into thin air. The team soon discovers she had an affair with a married professor, along with a lot of other seemingly unrelated events. When her body is found in a trash heap, the team has to find out what led to her death.
When a construction worker takes a fall from the twelfth story at a construction site, Grissom is convinced the victim is electrocuted. But as the Sheriff and a lot of others have no trouble believing it's a suicide and the evidence doesn't immediately support his theory, he has to go through a lot of trouble to prove murder. Meanwhile Nick and Catherine look into the death of a teenage boy who apparently suffered an epileptic seizure during a therapy session.
Grissom, Warrick and Catherine investigate when the class clown from a local high school is found dead in the boy's bathroom. They soon discover that there are a lot of suspects, as their victim bullied a lot of his fellow students. Meanwhile Sara and Nick try to find out the identity and cause of death of a badly decomposed body found in a leather bag.
Grissom, Warrick and Sara are sent to investigate when a former tenant leaves behind a blood-splattered apartment, and a missing girlfriend. Meanwhile, Catherine and Nick are confronted with what seems to be an urban legend turned fact: a scuba diver found in the top of a tree after a forest fire.
Grissom, Nick and Sara seem to have a clear-cut case when a young man is discovered burying a murder victim in the desert. Warrick and Catherine investigate the death of a young woman who died in a hotel spa.
Grissom and Nick investigate the death of a book restorer who was found dead in a locked library cage. Her autistic co-worker turns out to be a very reliable eyewitness. Meanwhile, Catherine and Sara handle the case of a young woman who was killed when her car was hit by a train.
A naked young woman is found dead in a sandbox at a park playground. The scars and liquid latex on her body lead Grissom, Catherine and Nick to a fetish club. Sara and Warrick investigate an armed robbery at a cash checking company.
Grissom, Nick and Warrick investigate when three men dressed as women rob a casino. Catherine and Sara are sent to investigate a murder at a remote convenience store. They soon discover the two cases are related.
When Grissom has to go to a conference, and Catherine is off to Reno, Grissom leaves Warrick in charge of the graveyard shift's investigation of the murder of a con man. Things get personal for Brass when he learns his estranged daughter Ellie is one of the suspects.
A famous real estate entrepreneur is found dead in a hotel elevator. It appears he died from natural causes, but the CSI suspect he was poisoned. But this turns out hard to prove as organs are donated and the body cremated.
Grissom, Sara and Warrick investigate when a young woman is found dead in a pipe at a construction site. Her sister is found nearby, also murdered. A likely suspect is one of the women's Internet relationship, an ex-con. Meanwhile Catherine and Nick look into a hunting mishap, but as their investigation develops, it begins to look less and less like an accident.
Serial killer Paul Millander returns, leaving another staged suicide. Upon finding a clue that connects all the victims, Grissom and Catherine end up in a court room, where the judge bears an uncanny resemblance to Millander. Further investigation reveals a startling secret about Millander's past.
Catherine gets involved in the kidnapping of a real estate developer's mistress. She has to accompany the man while he delivers a million dollar ransom. Meanwhile she tries to leave clues for the other CSIs who are on her trail.
When the body of a photographer is dumped at the Body Farm, Grissom finds out the man was shot to death, but there aren't any bullet fragments in his body. The case gets even more complicated when the CSIs discover the 12-year-old daughter of the photographer's girlfriend was the victim of child abuse.
Grissom, Sara and Catherine investigate when an ice hockey player dies in the middle of the game. Meanwhile Warrick and Nick investigate the apparent drug-related death of a saxophone player at one of the local casinos. During the case, Warrick finds himself attracted to the singer who worked with the victim.
Grissom, Sara and Nick investigate the death of four Buddhistmonks who were shot to death in their monastery near Vegas. Catherine re-opens the murder of an old friend, when the man that was convicted for the murder claims he is innocent. During the case she finds out some disturbing facts about how her old mentor handled the case.
The entire team investigates a bus crash in which nine people lost their lives. Before his death the driver claimed the bus began to vibrate, making it impossible for him to control the bus. The team has to find out whether the accident truly was an accident, or involved foul play.
A young woman is found murdered in her heavily secured apartment, clearly terrified of someone who was stalking her. The position of her body seems familiar to Nick, and as he and the others piece together the solution, Nick finds himself the stalkers next target.
Grissom, Catherine and Warrick investigate the murder of an elderly woman who lived alone with a lot of cats. Meanwhile Nick and Sara investigate an attempted murder with a pipe bomb placed in a car.
When a body is found buried in a park, covered in lye, Grissom and Sara discover the man was the victim of a hit and run. Meanwhile Nick investigates the death of a woman who drowned in the middle of the desert.
The former police chief of Las Vegas is found murdered and his 7-year-old daughter is found alive in Miami. Catherine and Warrick travel to Florida, where they assist the Miami CSIs in hunting down the killer.
The body of young woman is found in a shopping cart under a freeway overpass, her face horribly disfigured. The team soon discovers the victim was a fashion model and that her homeless sister is a likely suspect.
Grissom, Sara and Warrick investigate when a poker player drops dead at the table during a high-stakes game. Nick and Catherine investigate a dead body found in an abandoned air strip, which leads them to the world of street racing.
When a famous movie star (Chad Michael Murray) is accused of a double murder, his lawyer hires Grissom's former mentor to find errors in the CSIs' work. Things get even worse when their personal lives are used against them in the trial.
Grissom, Catherine, Nick and Warrick investigate when a wealthy couple is murdered at their house, which was up for sale. Meanwhile Sara is sent to a local high school where a cheerleader was found eviscerated on the football field.
Grissom, Sara and Nick suspect murder when the body of a dwarf is found hanging from a rope above the stage at a Little People's convention. Catherine and Warrick investigate a murder during a home invasion.
Grissom, Warrick and Sara investigate when a woman who was already missing disappears while taking part in a magician's act. Things get worse when the magician burns to death on the stage. But Grissom soon discovers that all is not what it seems. Nick and Catherine find evidence of murder when a rock star dies from an overdose in his trailer.
Fifteen years ago, Catherine helped to put John Mathers on death row for the rape and murder of a young student at a local college. On the day of his execution, he's granted a stay based on new DNA evidence. Meanwhile, Grissom, Nick and Sara are looking for a missing student, who is found murdered and left in exactly the same fashion as the women in Catherine's case.
Grissom, Sara and Warrick investigate when a boxer dies in the ring during 'Fight Night'. Nick quickly solves a robbery at a jewelry store, but finds reason not to close the case just yet. Catherine investigates when a gang member is shot at a parking lot.
Catherine, Sara and Warrick are left without a body or crime scene when a snuff film shows the real murder of a young woman. Meanwhile Grissom and Nick are trying to find the identity and killer of a body found in a tool chest, covered with fire ants.
A taxi driver is beaten to death by a mob after running over a boy with his taxi. When Grissom arrives at the scene, he finds out that the boy was already dying from a stab wound. When Grissom and Sara find the actual crime scene at a basketball court, they discover the body of a man that was shot to death. Are the two murders related?
Grissom, Nick and Warrick investigate when a body falls from the sky and lands between a couple of skateboarders. But soon Grissom's hearing problem forces him to leave the case to Nick and Warrick. Meanwhile Catherine investigates the death of a man who was shot with his own gun.
Grissom and Catherine investigate when the chef of a fancy restaurant ends up in a meat grinder. They soon discover a lot more went on in the kitchen than cooking. Meanwhile Sara and Warrick find out that the apparent suicide of a young woman who suffered from bipolar disorder is actually a murder.
When a raven is spotted with a human eyeball in its beak, it's up to Catherine, Sara and Nick to find the rest of the body and the killer. Meanwhile a normal autopsy turns into a special one when the victim isn't dead. David and Dr. Robbins manage to save his life, only to have him die later. Grissom and Warrick then try to find out who wanted the man dead.
When the nine-year-old daughter of Warrick's former mentor is killed in a drive-by shooting, Warrick lets his emotions lead him to assume a suspect is guilty without looking at the evidence. Meanwhile Nick investigates when a man is found dead in a sealed computer room. All of the victim's employees had reason to kill him, but none of them claim to have seen a thing.
Grissom, Catherine, Nick and Warrick investigate a 'peeping Tom' who escalated into breaking into women's apartments and terrorizing them. Meanwhile Sara reopens the murder case of a colleague's husband. The bullet that is still inside her friends body can help Sara find the killer, but her friend may not survive the operation to remove it.
In a special 90 minute episode, Grissom and Brass pay another visit to Lady Heather when one of her employees is found dead in a local club. Meanwhile Catherine is faced with a crisis when she has to save her daughter Lindsey from a flooded car and her ex-husband Eddie who was driving the car is found murdered.
Catherine and Warrick try to find evidence when the 5-year-old son of a professional basketball player is kidnapped. Meanwhile Grissom and Nick investigate when a man stumbles out of his car and dies...from a wooden stake lodged in the back of his head.
Sara finds out some disturbing news about her boyfriend Hank while she, Catherine and Warrick investigate a deadly car crash. Meanwhile Grissom and Nick find out that the death of a woman who died of carbon monoxide
