Gil Grissom and Sara Sidle come to the aid of a former colleague who is implicated in tampering with evidence; Maxine and the rest of the CSI team work the murder of a couple slain on their wedding day.
Max puts CSI on lockdown when evidence in a new murder tips Grissom and Sara to a new suspect in the crime lab; Folsom and Allie investigate a series of chilling killings at a dilapidated clown-themed hotel.
Catherine Willows persuades Maxine Roby to let her rejoin the team; a dominatrix is found murdered near her secret sex dungeon.
When three masked assailants invade a home and murder an entire family, the team is 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.
The CSI team investigates the eccentric world of sideshows when a couple of performers are discovered burned in a pit; Hodges mulls a plea deal as his criminal trial begins.
