Marg's Final 'CSI' - Who Wants to Kill Catherine?

Catherine Willows has been with the CSI team since day one of the wildly popular series, but tonight the crime-scene investigator will turn over her badge for good when she uncovers a terrifying plot to destroy her.

Elisabeth Shue Joins 'CSI' Cast

Reflecting on her life and career, the final episode of Marg Helgenberger's three-part goodbye has Catherine exploring her somewhat unsavory past to get to the root of a mysterious scheme to squeeze her out of the LVPD.

Exclusive Set Visit: Marg Helgenberger's Tearful Last Day of Filming 'CSI'

Don't miss Marg's final episode of CSI, airing tonight on CBS.