It's time for CSI fans to say goodbye to Nick Stokes.

Although Sunday's two-hour finale will resolve the season-long arc of the Gig Harbor Killer, all eyes will likely be on George Eads, as the original cast member departs the show after 15 seasons. "[We're] serving two masters," executive producer Don McGill tells TVGuide.com. "On the one hand we needed to wrap up the season arc and have an exciting conclusion, and at the same time [we had to] really pay tribute to the Nick character and give George Eads and Nick Stokes a star exit in the series. I hope the fans will be happy with the result."

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While Russell (Ted Danson) & Co. remain focused on stopping psychopath Paul Winthrop (Mark-Paul Gosselaar), Nick faces a tough decision when he is offered a chance to run his own CSI lab in San Diego. "Nick is grappling with the decision, but, as all our CSIs do, he soldiers on, even though he has this thing gnawing at him," McGill says. "We do resolve the serial killer story line and then that yields to a great denouement where Nick's choice comes to the fore. We really see him struggling with it and see him reaching out for help with the decision from ... the people who are closest to him and have been with him for this whole ride."

Indeed, Nick turns to colleagues Sara (Jorja Fox) and Greg (Eric Szmanda) for advice, which ultimately leads to a reflection of Nick's growth through the course of the series. "The evolution of Nick Stokes from the pilot to now has been a pretty rich character arc, which took him from a young CSI who was being mentored by Grissom [William Petersen] to the guy who inherited the mantle of Grissom," McGill says. "So, it made sense to consider an idea where Nick would go on to 'become' Grissom at another lab and make his name and reputation as a lab director. It seemed like the logical conclusion and culmination of that character arc from the pilot."

And it's because of the character's rich history that McGill decided to give Nick a happy ending. "The Nick character is so critical to the show and, in my mind, the success of the series, that there was never any discussion of killing off Nick," he says. "We always felt like the character is too important and too beloved — not just by the fans, but by those of us behind the camera. We always intended to give Nick an emotional and touching farewell, and one that also would leave the door open for Nick to come back. San Diego's not too far from Vegas, so who knows? There could be a CSI: San Diego!"

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While Nick will live to fight another day, not every character will. "It's possible that Paul Winthrop in some odd way gets the last laugh," McGill teases. "There is a cliff-hanger. We have a great tradition of our characters in jeopardy and, yes, we do leave our viewers with a question about the fate of one of our heroes." Adds co-executive producer Chris Barbour, who wrote the episode: "Sacrifices are made that will weigh heavily on Russell as we go into the next season."

But will there be a next season? Although the long-running procedural has lost some of its ratings steam since being moved to Sunday nights, McGill remains hopeful that the show will be able to resolve its cliff-hanger next year.

"We pitched the finale concept with the cliff-hanger to the network and they were very, very supportive of that idea," McGill says. "Obviously, there are lots of discussions about the fate ofCSI next year, and from everything we understand, the show ain't over. We have to work with that in mind and doing a cliff-hanger seemed only natural to us. We don't know what's going to happen exactly, but we're super hopeful that we're coming back, and, at this point, the network's given us no indication that that would not be the case. The finale leaves us with some unfinished business that we're eager to finish next season."

CSI's two-hour season finale airs Sunday at 9/8c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)