Everything We Know About 'NCIS' Episode 400

Mark Harmon David McCallum NCIS Season 9 Episode 15 Gibbs Ducky
Ron P. Jaffe/ CBS

NCIS is heading into its 18th season, which means reaching a milestone that few shows do: its 400th episode.

The special hour was supposed to be part of last season, before production shut down early (in March) due to the coronavirus pandemic. In fact, as executive producer Frank Cardea told TV Insider, they were supposed to begin work on the episode that focuses on Special Agent Leroy Jethro Gibbs (Mark Harmon) and his longtime friend, retired medical examiner, and historian Dr. Donald "Ducky" Mallard (David McCallum) a week and a half later.

"It's a very special episode. It's about Gibbs and Ducky and how they met. A case brings them back to 20 years earlier," he previewed of the hour that is going to air second in the upcoming season. And with the series exploring Gibbs' past, Harmon's son, Sean, is returning to play the younger version of the NCIS agent. (Sean last appeared on NCIS in its 200th episode, Season 9's "Life Before His Eyes.")

"The goal for this episode was to write a love letter to the longtime fans," Cardea has said. And with both Mark Harmon and McCallum (as well as their characters' relationship) part of NCIS from the very beginning, going back to when the team was introduced in two JAG episodes before the series was picked up in 2003, it's likely to be just that.

Filming resumed for the CBS procedural at the beginning of September, and the cast and crew has already wrapped production on the upcoming 400th episode, as series star Wilmer Valderrama (who plays Special Agent Nick Torres) shared on social media September 18.

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Some shows, like 'Supernatural,' haven't seen much change, while others only have one or two regulars left.

We're still waiting to find out when NCIS Season 18 will premiere, but when TV Insider spoke with Valderrama in September, he suggested we could begin seeing new episodes again in mid-November.

 

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Don’t wanna give anything away from #set... But... we just.. wrapped.. a little, episode. #NCIS SEASON 18 we on the saddle.

A post shared by Wilmer Valderrama (@wilmervalderrama) on

NCIS, Season 18, Fall, CBS