As Halloween descends on Sin City, the CSIs investigate when a creepy mannequin prop inside a popular haunted house turns out to be a real dead body. Also, Catherine enlists the help of Folsom to search for her friend who disappeared.
When three masked assailants invade a home and murder an entire family, including a pregnant woman, the CSIs are called to the scene to investigate. Catherine leads the team through the emotional case, which intensifies her own longing to reconnect with her estranged daughter, Lindsey.
After all the guests attending an upscale fundraising soiree for the science department at a local university fall ill, the CSI team gears up to investigate. Also, Catherine enlists Grace’s roommate to help her find clues after Grace disappears.
Catherine’s frustration intensifies when a lead suspect in Grace’s disappearance is found murdered. The team exhausts all their skills to figure out who killed the suspect, and if his death will lead them to Grace.
When the bodies of two Regency Romantic Festival attendees are discovered, the CSI team uncovers a shocking link between their murders and previous cases.
A social media influencer party ends with the brutal murder of a popular guest. Chris Park's side hustle makes him uniquely qualified to lead the CSI team in their investigation.
When a young, non-verbal boy is found hiding in a stranger’s garage, the CSI team searches for his missing mother. Also, Max receives a strange letter with symbols in silver ink that Folsom and Allie recognize from prior crime scenes.
Catherine’s day off with her granddaughter gets interrupted when a woman wakes up from a four-year coma and remembers details from the night her sister died.
The CSI team investigates the death of an archaeologist found near the breakthrough discovery of an ancient civilization. Also, Max locates another cryptic note written in familiar silver ink after a mentally distressed woman kills her attacker.
The CSIs investigate the mysterious death of a competitive eating contestant, and Chavez partners with Allie to prove where the mysterious silver ink notes have been coming from.
A silver ink note threatening Maxine Roby's life is found at the crime lab, sending the entire CSI team to crack who is behind the notes and how they connect to other murder case.
Medical examiner Sonya's life is in jeopardy when she is exposed to a mysterious poison as the CSI team races to find the antidote and the silver ink murderer who appears to be targeting the Crime Lab. Max's ex-husband, Daniel, returns to make sure that she and their son are safe.
When the body of a young girl who was killed over 40 years ago is discovered at the bottom of Lake Mead, Max Roby promises her mother, Raquel Williams, that the CSI team will finally find justice for her daughter. Also, Greg Sanders brings his quirky humor as he returns to the crime lab.
When wrongly accused former suspect Gene Farrow enters the Crime Lab covered in blood, wielding a cleaver and looking for Allie Rajan, the CSI team investigates his peculiar story about a macabre party with a fatal ending.
The CSI team investigates a case where an ambitious investigative reporter is found dead at a peanut factory. Also, everyone in the crime lab buzzes over who Max will promote to day shift supervisor.
The CSI team investigates a murder case that hits close to home for Folsom. When he is forced to sit this investigation out, he does his own digging with help from Trey. Worried Folsom will do something he regrets if he gets his hands on the killer, the team find themselves racing to arrest the suspect first.
