Ted Danson, Peri Gilpin and Marc Vann Ted Danson, Peri Gilpin and Marc Vann

On CSI, the name Jeffrey McKeen is basically synonymous with danger.

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That certainly holds true in the CBS drama's Season 13 finale (Wednesday at 10/9c). When one of the mayor's key supporters is suspected of murdering his own wife, D.B. Russell (Ted Danson) & Co. are tasked with clearing his name. In the process of doing so, however, the team learns that McKeen (Conor O'Farrell) may be behind the murder, despite the fact that he's behind bars for killing former CSI Warrick Brown.

"The old coming back to threaten the new was intriguing to us," executive producer Don McGill tells TVGuide.com. "What if one of the great villains of our past came back to bring back painful memories and ghosts from the past, but also threaten our CSIs? ... What ensues is a threat to Russell's leadership —his sense of righting the ship — but also a series of personal threats to our CSI team."

The professional threats come first, as McKeen's band of dirty cops begin to manipulate evidence in a way that turns suspicion toward the Las Vegas Police Department. Not helping matters is Finlay (Elisabeth Shue) and her by-any-mean-necessary style of investigating. It's not long before she and Russell are butting heads.

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"The case is reminiscent of the case that got Finlay fired in Seattle," McGill says. "It dredges up deep feelings from the past between Finlay and Russell. Finlay is someone who has a tendency to, in her quest for justice, cross the line. Russell sees the bigger picture. We'll see whether Finlay has learned from the past."

But Finlay's frustration with Russell may not be just about the work. "For Finlay, [Russell] is the ideal man that is both attractive but unattainable," McGill says. "He is that person she wishes she had met. Russell and Finlay have a great working relationship, and there is definitely a fire there. But for [Russell] the fire is all about the work. For Finlay that's a frustration."

The finale will also offer viewers a glimpse of the other woman in Russell's life, his wife Barbara (Peri Gilpin). "We wanted to create a character... who is warm and funny and strong — someone who really is the keeper of the hearth and the intellectual equal of D.B. Russell," McGill says. "She is both intriguing and a soul mate — someone [who was] willing to leave a high-society life and create a new life. Being the wife of a cop is an interesting choice for any woman."

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It's also a dangerous choice. Indeed, the expansion of Russell's family in the finale conveniently happens just in time for them to play a major part in this season's cliff-hanger.  But the Russells aren't the only target: At least two other major characters will be put squarely in danger before the credits roll.

And while Nick (George Eads) may not be faced with any physical danger at McKeen's hand, he will face a life-altering choice once McKeen's plot exposes the corruption with the LVPD. "By the end of the finale, [Nick] will be in a place where he's questioning how the wheels of justice work and also questioning his role in that system," McGill says. "It will bring him to an existential crisis where he really, really contemplates whether or not he wants to be a CSI anymore."

The CSI finale airs Wednesday at 10/9c on CBS.