'NCIS': Wilmer Valderrama, Sean Murray Tease 'Unexpected' Finale Cliffhanger, 'Dark' New Chapter (Exclusive)

ET was on the set of the season 20 finale and spoke with Murray, Valderrama, Katrina Law and Gary Cole about 20 seasons.

NCIS is wrapping up its 20th season in style! ET's Matt Cohen was exclusively on the set of NCIS for Monday's finale, where Sean Murray, Wilmer Valderrama, Katrina Law and Gary Cole reflected on the CBS procedural's longevity and teased what's to come in the dramatic, "unexpected" season closer.

"It's amazing. I mean, the fact that we're not only still here we've got the incredible support of our fans who have been with us from the get-go pretty much and are still with us and still going," Murray, who is one of the sole remaining cast members from season 1, told ET of accomplishing 20 seasons. "We're gonna keep plugging away as long as they let us."

The newer cast members expressed gratitude for those who paved the way and kept the lights on for NCIS to continue to thrive, two decades in. "I had no idea that season 20 of NCIS was going to become my dream job," Law admitted. "But thanks to Mark Harmon and everybody that came before me. Hopefully it just keeps going."

"The fact that this show 20 years later, can still not only be welcome in people's homes, but be still up and running and still be swinging and everyone's still happy to be here. Still excited to keep swinging and the writers are still keeping it fresh, and the actors are not tired is a testament to the efficiency and most importantly the love that everybody puts into this," Valderrama said. "We like it here and we have a lot of fun."

"This show went on a year when dinosaurs roamed the Earth," Cole quipped, before getting serious. "No, it's extraordinary. I've been here since the beginning of last season, season 19. So when you come through the door there's people here that have been here the whole time and even before that... It's pretty incredible. "

CBS

Another season is almost in the books. And this time, Torres (Valderrama) finds himself in prison as the team tries to stop an impending terror attack on U.S. soil in the season 20 finale, titled "Black Sky."

"They allowed us to do something really loud," Valderrama, who was rocking a buzz cut during the set visit, said of the episode. "We do a major cliffhanger and it's not just the case that has to close, it's actually a new chapter -- a dark one -- that may open up for Torres, as well as how it affects all of us as a team and as a family."

"Torres may go back to some of these rogue days and getting in some trouble," he teased. "There is something that happens towards the end of this episode that you don't see coming. We might get the bad guy of this episode, but we introduce another big bad [by the end of it]."

Added Murray: "The fans are going to be left with quite the cliffhanger. We always like to end on usually something that's going to leave little tastes and we'll see where we come back to."

Law elaborated further on the cliffhanger, describing it as "unexpected" and, as Valderrama hinted earlier, saying that it "comes out of nowhere."

"And it really makes you wonder what's going to happen," she said of the potential impact it may have on season 21. "Myself, I'm kind of like, 'Oh, it's dark and it's deep."

The NCIS finale airs Monday, May 22 at 9 p.m. ET/PT on CBS.

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