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.

The CSI team investigates after a group of teens discover a dead woman behind the wheel of an abandoned car in a Nevada ghost town.

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.

Max leads her team to investigate the death of a prestigious Michelin-starred chef found hanging in his restaurant’s walk-in freezer.

A mysterious bigfoot-like footprint found near a crime scene puzzles the CSI team as they work to uncover who - or what - killed a father and son.

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.

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.

After an explosion in a bio lab, the CSI team races to determine which nerve agent left one of their own unconscious, while the others explore a dangerous underground tunnel to find another CSI who got kidnapped during the blast.