Elisabeth Shue Elisabeth Shue

Out with the old, in with the Shue.

Wednesday's CSI began the process of replacing Marg Helgenberger's Catherine Willows. It did so with the introduction of Elisabeth Shue as Julie "Finn" Finlay, a blood-spatter expert brought in by D.B. Russell (Ted Danson) to sort through a particularly grisly and confusing crime scene. And one thing's for sure: These two have complicated history.

Marg Helgenberger says goodbye to CSI

Although Finn initially rebuffs Russell's invite to consult for the CSI team ("We know how it ended last time," she says), it's clear she has respect for the man. After all, the first time we see Finn echoes the way we met Russell earlier this season: lying in the middle of a crime scene. "You think you hate me," Russell tells her. "But that whole lying on the floor playing the victim thing kind of says you miss me."Soon enough, Finn comes around and offers to take a look at this particular case. But she sets strict ground rules. Chief among them: "We are never going to talk about the past," Finn says.So, what's the big secret? "Russell, as far as he's told Catherine, has only... slept with one woman and loved one woman in his life," executive producer Carol Mendelsohn

says. "But we will find out that Finn was his work wife. That's a really interesting relationship." Adds executive producer Don McGill: "The characters have great chemistry and I think they have a very interesting, very intimate relationship professionally."

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Indeed, Shue and Danson's scenes were playful and fun. Much like Danson has done all season, Shue brings a lighter energy to show, which is a nice relief from the sometimes bleak subject matter.In the end, Finn proved her theory that "blood spatter can often tell you more than a test tube." Although the team had a prime suspect based on DNA evidence, Finn's blood analysis proved his innocence. And that was good enough for D.B. (short for Diebenkorn, it turns out) to offer Finn a regular gig with the graveyard shift."Maybe I'll call you," Finn says as she walks away. Spoiler alert: She'll be back.What did you think of Shue's character? Do you like the chemistry between Russell and Finn? Watch a clip from the episode: