The CSIs face a year of challenge and change as they say goodbye to some of their long-time team members and welcome new ones to the night shift. Grissom, Catherine and the rest of the group deal with the aftermath of Warrick Brown's shooting, and then must adjust to the irreverent personality of new CSI Riley Adams (Lauren Lee Smith). Later in the season, the team will be in for a shock when revered leader Gil Grissom bids goodbye to Vegas and a new CSI, simply known as "The Professor," (Laurence Fishburne), joins their ranks.
The episode begins with Warrick dying in Grissom's arms. The team successfully uncovers the fact that undersherriff MCKean is behind the murder. They go about proving that he set Warrick up to take the fall for gedda's murder. When Warrick was exonnerated, McKean realized that Warrick would never stop looking for the real murderer. This is what made him a great CSI. This episode ends with Grissom speaking at Warrick's funeral. Sara returns in this episode to be with Grissom.
Nick and Catherine investigate why a woman who was about to be married would have taken a swan dive off of her balcony. Also Grissom investigates the brutal murder of a woman found in an alley. The investigation gets tougher with the discovery that her two-year-old was with her when she was murdered.
This is a quirky episode where a twisted artist poses dead people as if they are still alive. He poses them at park benches, on cell phones standing at lightposts, and at bus stops.
Nick and Riley witness a man in a police costume rob a convenience store. They then must help the rest of the team investigate the death of a young woman who turns out to be the daughter of a big time drug lord wanted by FBI, CIA, and DEA. They discover with security camera footage that she was thrown out of a club by two bouncers earlier that night. When Catherine and Riley go to the club Catherine discovers her daughter Lindsey there with a fake ID.
The murder of a seemingly clean-cut young man has the CSIs delve into the erotic world of S&M. The victim, Ian Wallace, was tortured before he was killed and left by the side of a road.
The unfortunate story of a young boy who's mother has HIV, and so does he. The CSIs find that his kind uncle has been trying to protect him from his abusive mother. They are Korean and live in Koreatown, where people just do not talk, even when there is a shooting in the streets. The result is that the abusive mother shot the uncle, and the boy shot his mother in order to escape her abuse.
Husband and father, Peter Rowe, is immediately the prime suspect in the murder of his wife and attempted murder of his 7-year old daughter after CSI investigators figure out that he was the main suspect in the murder of a P.I, Trevor Murphy, more than 12 years ago. Rowe, aka Mark Redding, had since changed his name to hide from his past. Rowe's interrogation leads investigators to Murphy's children, who always believed Rowe was their father's killer. With revenge on their minds, they tracked down Rowe with the intent to kill him, instead finding his wife and child. CSIs also look into the deaths of two teenage boys in what initially seemed like a case of drunk and reckless joy-riding. Through forensic evidence investigators find that this was no accident -- a frustrated old man wanted to teach those boys a lesson on the dangers of vandalism.
The death of a young and beautiful new talent takes the CSI invesitgation back 50 years to solve the present day crime. Layla, a popular singer on a nationally televised talent show, is found dead outside an infamous Las Vegas nightclub that has been shut down since the owner's murder 50 years ago. Investigators find the victim has a dark secret to hide that could have ruined her career but forensics leads CSIs to a surprising conclusion. While trying to piece together the odd circumstances of the young woman's death, investigators find that the old man living in the nightclub, who was a suspect in Layla's death, may have an intriguing connection to the place in its hayday and a hand in the club owner's murder. Grissom delves back into his old life as a card shark to gets answers to the decades old crime.
The discovery of a garbage bag containing a badly decomposed body leads CSIs to open up the case files of the infamous "Dick & Jane Killer", Nate Haskell. Eleven years ago Haskell went on a killing spree targeting at least seven young couples which he is now serving a life sentence. Unexpectedly, mito-DNA testing revealed hairs from the victim match Nate Haskell; sending the CSIs to theorize that Haskell had accomplices and our victim may have been one of them. Forensic evidence found in the victim's home, thought to be his killer's, is then linked to the murders of Ian Wallace and Justine Stephani; this is the unsolved murder of the couple we saw in episode #905 "Leave Out All The Rest". Grissom secretly joins the class of a well-known criminal pathologist Dr. Raymond Langston (Laurence Fishburne) who assists Grissom in getting Haskell to reveal the location of his first victim but simultaneously sends CSIs into a whole new realm of this case when a new male body is found murdered next to the remains of his first victim. The case in ongoing and will be picked up in a future episode. Equally shocking was Grissom's stunning announcement to the team that he will be leaving CSI.
The CSIs continue to search for the accomplice in the Dick and Jane murders. Investigators work against the clock to find the missing wife of the newest male victim, seen at the end of episode #909, that was found at the burial site of the first D.J.K victim . They believe she is still alive and are taking a second look at the evidence to see if they can uncover any new clues. Dr. Langston (Laurence Fishburne) has been brought onto the new D.J.K task force, at Grissom's request, as a Special Consultant; he helps Grissom get into the mind of Haskell even going to meet with the infamous serial killer to try and trick him into divulging the whereabouts of the missing woman. Soon the CSI team identifies the suspect and finds the location of the home where the killer has taken the missing woman to torture her. The killer is brought down and the woman is found alive thankfully ending the D.J.K killing spree. Grissom realizes that with the conclusion of the D.J.K case his time as a CSI has ended and offers Langston a spot on the CSI team. With his departure, Grissom surprises Sara and gives her the news that he has left CSI.
It's the first day on the job for Langston (Laurence Fishburne) as the newest CSI team member. While initially thinking his first day would include only a simple burglary call, he and the team are soon called to solve an arson and homicide case. The victim, a local gym owner, was found burned in the ruble of his home. CSIs find he was murdered before the fire was started and begin to uncover financial as well as marital problems that give cause for a number of people to want him dead. Investigators are puzzled by what started the fire and Langston is instrumental in figuring out the unusual detonating device which accompanied by video surveillance from the gym leads CSIs to the victim’s housing contractor; who committed the murder because he was in love with the victim's wife. What was a simple burglary touches a nerve with Langston as a young boy is forced to help police catch his mother for the crime. With Grissom's departure, the team is trying to adjust to life without him and Catherine takes the step she feels will allow her team to begin moving on.
When an FBI agent is brutally murdered in a gas station restroom the CSI team is called in to work with the victim's partners in order to find the violent killer. The FBI agents were working undercover to try and break-up an underage prostitution ring which appears to have contributed to his murder. As CSIs piece together the crime scene evidence they find an ultimate fighting champion hired by the leader of the prostitution ring was the likely killer. When confronted by officers, the suspect kills himself in front of hundreds of spectators. The team believes the case has come to a close as FBI headquarters gives them startling information; the victim was not an FBI agent and neither are his partners, who worked closely with Langston and Brass on the investigation; they are actually mental patients. When another one of them is murdered, CSIs know they must find the last "agent" before the ring leader does. Langston is the only one that can reach the surviving "agent" after he has a mental breakdown. With his help, the team takes down the leader of the prostitution ring and saves dozens of underage girls.
Langston and Nick are called to investigate what appears to be a robbery gone bad in a local Fast food restaurant after the manager is found dead and two other employees are missing. The evidence, being covered in cooking oil, is a task for forensics to decipher but after finding the missing male employee in an oil drum and the other female employee alive and well, the pieces fall into place. The manager turns out to be less than a gentleman when he tries to take advantage of the female employee he knows is an illegal alien. When the male employee walks in on this and tries to protect her, the manager kills him and the illegal employee runs out of fear of being blamed. In a twist of karma, the manager is accidentally killed after he slips and falls after dragging his victim outside. Catherine and Brass are called to an equally strange death that they initially believe the husband bound and murdered his wife and then find that he was setup and the wife had a bizarre means of committing suicide; death by toothpaste.
When Langston testifies in the trial of a respected Congressman, new evidence sends the CSIs back to the lab to reopen the investigation.
CSIs are called to three different crime scenes in one night. While initially believing the murders are unrelated, each of the team members investigate the crimes separately, gathering forensics and piecing together the chain of events. Each finds a prime suspect in their cases but as they begin to compare information the team soon discovers that one con-man is the link between all three of these deaths.
When the CSIs are called to a murder scene at a familiar motel, Nick is thrown for a loop as he pieces together three separate murder investigations that all took place at the same establishment over the course of a year.
The CSI team investigates a shootout in a normally quiet Las Vegas neighborhood with dire consequences.
Langston and the team must investigate the murder of his former student after CSIs are called to the scene of her murder. The young woman was researching the 11 year old case of three women killed by a known, but since dormant, serial killer for her graduate thesis; it appears she got close to figuring out the killer's identity and the killer came out of hiding to make sure she did not expose him.
Nick's case of a deceased skydiver takes an interesting turn when Catherine discovers there may be a connection between the skydiver and a mysterious double murder case.
When the "star" of Astro Quest Redux is found murdered at a science fiction convention, assorted freaks and geeks are obliged to boldly go under the scrutiny of the CSI team.
The team arrives at the scene of a triple homicide in a supposedly quiet neighborhood where a little girl witnessed her entire family getting killed. The only thing the team has to go on is the girl's description of a scar on the man's arm. Also, Nick is back on duty after his recent run in with Internal Affairs.
A series of indeterminate deaths test the deductive powers of the CSI team, who fear that a public health emergency may be in the offing. Meanwhile, a friendly rivalry over who will win an upcoming bikini contest takes a deadly turn...
A band of vicious bikers is given the go-ahead to take down one of their own when it's discovered that the guy is an undercover cop.
Greed leads to murder and destroys the lives of five people when two of them discover a stash of old casino chips worth $1,000 each on the collectible market.