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.
A family is brutally slain by three masked intruders, one victim being pregnant. Catherine heads the investigation, the emotional toll deepening her desire to reunite with her estranged daughter, Lindsey.
At an upscale science department fundraiser, guests fall ill, prompting a CSI investigation. Meanwhile, Catherine seeks Grace's roommate's aid when Grace goes missing.
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 granddaughter joins the team in investigating a case from when Catherine was in charge. A victim has woken from a 4 year coma and revealed that her poisoning was not the accident it had been ruled originally.
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 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 cases.
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.
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.
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 pistachio 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.
