'CSI' 300th Episode: Marg Helgenberger Returns To Solve A Cold Case (EXCLUSIVE VIDEO)

This Wednesday (Oct. 23 at 10 p.m. ET on CBS), the landmark 300th episode of "CSI" will air, bringing back fan-favorite Marg Helgenberger as Catherine Willows. The character returns to help the CSIs solve a cold case that has haunted the team for 14 years.

In HuffPost TV's exclusive clip, above, watch Helgenberger in action in a "faux-back" scene in which Catherine and Sara (Jorja Fox) are arguing with Conrad (Marc Vann) about the unsolvable case, which stretches back more than a decade and was once quite a source of contention between them.

"Beverly Hills 90210" alum Jason Priestley is also set to appear in the 300th episode as a casino mogul who "once threw the most lavish parties in Las Vegas, until a scandal tainted his reputation" and turned him into a recluse.

Are you looking forward to "CSI's" milestone 300th episode?

CSI 300th Episode