Grissom is heading back to Vegas.

CBS announced on Wednesday that "CSI" would end after 15 seasons but not before wrapping up the flagship series with a two-hour TV movie that will feature original stars William Petersen and Marg Helgenberger.

The "CSI" movie will air on Sunday, Sept 27.

Petersen left the series during season nine and was replaced by Laurence Fishburne. Helgenberger made her exit during season 12 and was replaced by Elisabeth Shue.

Ted Danson, who served as the CSI team leader for the final four seasons, will transfer over to the spinoff "CSI: Cyber," starring Patricia Arquette. Arquette appeared in two episodes of "CSI" with Danson to introduce her "Cyber" character, Avery Ryan.

CBS had no other casting announcements for the movie. The remaining cast included longtime stars Jorja Fox, Eric Szmanda, Robert David Hall, David Berman, Wallace Langham and the recurring Marc Vann as well as Shue and Elisabeth Harnois. Original stars George Eads and Paul Guilfoyle left the series at the end of season 15 and 14, respectively.

"CSI: Cyber" is the last show of the storied franchise left standing on the CBS schedule.