Rocky Carroll Previews 'NCIS' Franchise's 1,000th Episode: 'All Hell Breaks Loose' (Exclusive)

The 1,000th episode of the 'NCIS' franchise premieres tonight at 9 p.m. ET on CBS.

After over 20 years and four spinoffs, the NCIS franchise is going to celebrate its 1,000th episode, and Rocky Carroll spoke to all about it. In Season 21, Episode 7 of the Mothership, appropriately titled "A Thousand Yards," NCIS is under attack by a mysterious enemy from the past. At the same time, Carroll's Director Leon Vance tries to mend his relationship with his estranged son by explaining why he chooses to stay at NCIS, despite the ongoing dangers of his job.

Carroll previewed what Vance will be dealing with, noting that while his daughter has grown up and is now an NCIS agent, Vance's son "is not so enamored with the agency." He continued, "NCIS has a whole different meaning for Vance's son than it does for the director. And we find out that the two of them have a strange relationship, to say the least. And as they're trying to work to patch up this fractured relationship, all hell breaks loose, and we need the NCIS team and some visitors from the NCIS universe to help us get back on track."

Considering Vance lost his wife due to something that NCIS was wrapped up in, it's not surprising that his son still has reservations about his father's job. It also doesn't help that the entire agency is under attack by someone who has a past connection with NCIS. Vance will be dealing with a lot, both personally and professionally, and it's very likely fans will be in for an emotional roller coaster.

(Photo: Robert Voets/CBS)

As for those "visitors from the NCIS universe," it was previously announced that Daniela Ruah from NCIS: Los Angeles and Vanessa Lachey from NCIS: Hawai'i will be lending a hand to their D.C. brethren, and there's no telling who else might show up or who that mysterious enemy from the past is.

Even though the milestone episode essentially centers around Director Vance, Rocky Carroll said he didn't even realize it was happening "until we were in production" that it would be the 1,000th episode. He shared, "Fortunately, somebody didn't sit me down in a room and say, 'The episode that we're about to do is the seminal 1,000th episode.' I probably would've been a little bit more freaked out. We were just shooting another episode. It was another episode in the season. And somewhere along the line, we may have even finished filming it. Then I realized, 'Oh, this is the seminal episode.' So fortunately for me, they didn't give me too much preamble about the importance of the episode."

It's crazy to think that the NCIS franchise is hitting 1,000 episodes, but it's continuing to grow with more spinoffs on the way, and it sounds like there is going to be a lot to look forward to. Fans will have to tune in tonight, Apr. 15, at 9 p.m. ET to see what happens in the milestone episode.