Enredo

An explosion inside a casino brings Catherine Willows back to Las Vegas to investigate. And when the crime is tied to Lady Heather, Gil Grissom is brought back as well to aid the investigation.

On the special two-part series finale, Grissom and Willows return to help the CSI team solve a catastrophic case that paralyzes all of Las Vegas. Past and current series stars scheduled to appear include William Petersen, Marg Helgenberger, Ted Danson, Jorja Fox, Eric Szmanda, Robert David Hall, Paul Guilfoyle, Wallace Langham, David Berman, Elisabeth Harnois, and Jon Wellner; Melinda Clarke also returns as Lady Heather. (Part 2 of 2)

When a bomber strikes in a hotel, the team investigates. Catherine returns because the casino is her family's. Evidence found at the scene leads them to suspect Lady Heather, and when she can't be found, Grissom is asked to come to Vegas to help. He arrives and clearly things between him and Sara are a little tense. And everyone is sure Heather is involved, but Grissom doesn't think so. And when other bombings occur, they try to find out who is responsible.—rcs0411@yahoo.com

Lady Heather (Melinda Clarke), a principle in cases worked on by CSI Las Vegas over the years, to the point most all of the staff has an understanding of her profile, is implecated in an ongoing series of suicide vest bombings. Gil Grissom (William Petersen) is called back into this operation based on his background knowledge and continued relationship with Lady Heather and Catherine Willows (Marg Helgenberger) who becomes involved in the process because the initial bombing happened at her family's casino.

Old relationships have new chapters added in a vexing two episodes that have all involved doing their best to solve the CSI puzzle presented in this series finale.