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.

The CSI team investigates a bomb that detonated during a masquerade party for wealthy investors at the site of a new casino.

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.

With their respected colleague Josh Folsom under arrest for the death of Kahn Schefter – the man responsible for killing Folsom’s mother – the CSI team combs through every crumb of forensic evidence to determine his innocence or guilt.