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, from car to shoes. Another body is found wearing only his boxers, with signs of a clown's make-up.

Greg has found a replacement in the DNA lab, Chandra Moore, and introduces her to the co-workers. Capt. Brass, Grissom and Greg, in his first case, investigate the death of an unidentified victim with a shot in the forehead in a shooting in the nightclub owned by Manny Brazil. He says that he does not know how the gun has passed through the metal detector. Catherine and Det. Louis Vartann investigate the murder of a woman covered in blood in a hotel room. The man, Carl Johnson, also covered in blood, tells to the detectives that he has never seen that woman before. Soon they learn that the victim is the stripper Nicole "Raven" Richards that drugged Carl to rob him. Warrick and Det. Chris Cavaliere investigate the death of Lance Frazer, a loser that died in the bathtub electrified by heat exchanger causing a short circuit in the motel. Soon Warrick learns that Lance hit a fifty-thousand-dollar jackpot on the previous night. Nick, Sara and Det. Travis investigate an "alien" buried in a shallow grave near the Area 51.

When the body of Vanessa Keaton is found drowned in water fountain in a gated community and hit on the forehead, Grissom, Sara, Greg and Capt. Brass assume the investigation. Soon they learn that Vanessa was in a swingers' party, but the water in her lung is not from the fountain. They interview the owners of the house and guests and collect the water in the swimming pools to see if any of them match the water in the lungs of Vanessa. Mia examines the DNAs in the several condoms in the garbage bin. Meanwhile, Warrick, Nick and Det. Chris Cavaliere investigate the murder Mr. Basengi, the landlord of a video arcade. They find an eviction notice to the tenants are Melissa Poolie and Charlie Pinscher that become prime suspects. They visit Charlie that tells that Melissa was his girlfriend and left him with the rent. They learn from Marty Gleason, a member of the crime scene cleanup, that the place has a decomposed smell and Warrick and Nick find the body of Melissa hidden in a game and Charlie is brought back to the interrogation room.

Greg is doing his final proficiency test and he has a case to solve. Ironically, he investigates the death of a Sherlock Holmes- wannabe, obsessive to the point of recreating the great detective's living room in his home. He died from a close-range gunshot wound. The murder weapon is not found in the scene although everything other pieces of evidence suggest that it was a suicide. Working under Catherine, Nick and Warrick works on a case of a dead guy found in his car which veered off the highway. Dr. Robbins cannot find the cause of death and it is left to the two detectives to solve the mystery.

When the flight attendant Martha Krell is found dead and raped in her hotel room, Grissom, Greg, Sara and Capt. Brass investigate the case. They note that there is no luggage in the room that was cleaned and sanitized without any evidence. Ecklie tells Sara that he had a similar case five years ago, with the flight attendant Sue Stein. Sara notes that the present technology is able to retrieve the fingerprint from the previous case. Meanwhile, Catherine, Nick, Warrick and Det. Chris Cavaliere investigate the case of the death of the twelve-year-old Ty Hawkins, who has been beaten to death on his bed while sleeping. His fourteen-year-old brother Matt becomes the prime suspect to Det. Cavaliere and when Matt confesses the murder of his brother, Nick questions the way Det. Cavaliere conducted the interrogation. The CSI team proceeds the investigation and finds two other suspects: Ty's father Martin and the homeless Walter. Who might be the murderer?

When a Hummer in the wrong way runs over an old Fiero, Grissom meets Capt. Brass to investigate the scene. He learns that the Hummer's driver has fled and the Fiero's driver is alive in the hospital. At a car convention, when the host Mr. Daluca opens the curtains to show the latest RV model to the audience, there is a dead woman. Warrick and Det. Louis Vartann learn that the victim is the twenty-nine-year-old model Lisa Schumacher. Dr. Robbins tells Catherine that Lisa was asphyxiated and she had sex before her death. Daluca becomes their prime suspect. Meanwhile, the model Gwen that is working at the convention, goes to the house of her personal trainer Paul Charles to workout and sees him dead through the window. Greg and Sara investigate the crime scene while Dr. Robbins carries out the autopsy. When he sees a black substance in his eye, Hazmat takes Sara and Greg to the decontamination shower. When the body of a boy is found on a bus stop bench covered by a blanket in front of a laundromat, Nick investigates the case. Dr. Robbins tells Nick that the cause of death was asphyxia from heat damage. They identify the victim is Chase Ryan and Nick tries to understand what might have happened to the boy.

After a massive shootout between the LVPD and a Latin American mob gang, the CSI team have to find and process hundreds of bullets to determine exactly what happened.

The CSIs continue to process the evidence collected from the high-speed chase. They must also find the bullet which killed a police officer to determine who shot him.

CSI needs the help of an 8-year-old, HIV-positive boy to figure out who shot and killed his uncle and his mother during a street party in Koreatown.

A man blames the anonymous sender of emailed death threats after his wife and daughter are shot. Two teens in a convertible crash into a tree; one has an inexplicable shoulder injury. Grissom attends a transfer hearing.

CSI gets three new dead bodies, and all three cases have a connection to the same con artist with multiple identities.

After finding a new dead body, Langston and Brass uncover a connection to an unlicensed doctor who may be "Dr. Jekyll." Meanwhile, Willows discovers that two women found dead in a hotel were con women who preyed on an unsuspecting actuary.