Marg Helgenberger is returning for the 300th episode of CSI: Crime Scene Investigation, set to air October 23. Helgenberger, who’s starring in the new CBS drama Intelligence, will reprise her original character Catherine Willows who returns to help solve a cold case that has haunted the team for 14 years. The milestone episode will be celebrated without the other original longtime lead, William Petersen, who played Dr. Gilbert “Gil” Grissom. Helgenberger appeared for 12 seasons on CBS’ CSI before her last episode aired on January 25, 2012. The 14th season of CSI premieres September 25 at 10 PM.