Marg Helgenberger is coming back to CSI as Catherine Willows for the show’s 300th episode.

Marg Helgenberger played Catherine Willows on CSI family for 12 seasons. She’s putting back on the gloves this Wednesday as the show celebrate its 300th episode.

As Catherine Willows, Marg Helgenberger will help the CSI team solve a 14-year-old cold case. The CSI team runs into a murder that looks suspiciously like a case from 14 years ago. Marg Helgenberger play Catherine Willows in some flashback scenes and then be called in to join the team on the new, old, case.

Executive producer Don McGill says “We will flash back 14 years to seminal moments that show Catherine, Nick, Sara, Greg and Ecklie as they were, [and how that] informed the evolution of the characters now. It’s going to be a really fun episode, very emotional, that honors 14 years of CSI.”

Marg Helgenberger’s Catherine Willows was always one of the fan’s favorites.

Don McGill said “We were just really excited to have Marg come back because, obviously, she’s such an important part of the history of CSI… And she was super excited. It was kismet!”

Marg Helgenberger reminisced with TV Guide about past CSI episodes recently. Helgenberger remembered “Fur and Loathing.” In the fifth episode from Season 4 the CSI team was probing the case of a man dressed as a raccoon found dead by the side of the road. It turned out that he was part of a subculture called “furries,” people who wear animal costumes for fun.

Helgenberger said “I didn’t know much about this world, so before we shot the episode, the director and I went to an event where people came wearing tails. A lot of the extras we used were actually into that. God bless them.”

Marg Helgenberger will return as Catherine Willows on the 300th episode of CSI: Crime Scene Investigation on Wednesday at 10 pm EST.