Mark Harmon has officially played Leroy Gibbs on NCIS for 400 episodes. Harmon, who is the only full-time cast member from the 2003 pilot, also acts as the series’ executive producer.

The show jumped back in time for the 400th episode, which aired at the end of November, to show fans how Gibbs met Donald “Ducky” Mallard (David McCallum). Sean Harmon, Harmon’s son, played a young Gibbs in the landmark episode. Sean is a small part of NCIS history, and the 69-year-old admits “there’s pride involved.”

The 400th episode of ‘NCIS’ was broadcast in 1980.

According to TV Line, the 400th episode of NCIS, titled “Everything Starts Somewhere,” moved back to 1980. The story begins 40 years ago, when the family who brought Gibbs and Ducky together for a case 40 years ago unexpectedly returns.

During the flashbacks, Sean Harmon and Adam Campbell reprised their roles as young Gibbs and Ducky. Back in 1980, NIS (later NCIS) was investigating a cr1me scene where someone in a Mercedes was driving on the wrong side of the road.

A civilian accountant with the rare LEOPARD syndrome at the Department of Defense swerved to avoid the car.

He had been stabbed before to the accident and d1ed as a result of his injuries. He also had a cash bag and a revolver in his car, as well as Sergeant Gibbs in the trunk.

This is the point at which Gibbs meets both NIS and the Zucados cr1me family. The young Ducky was driving on the wrong side of the road in his Mercedes.

Gibbs’ life was saved as a result of his driving error. To repay him, he buys Ducky a drink at each of the city’s bars for three days in a row. The two eventually reunite with the Zucado family before parting ways.

“You’re a terrific man, and I hope we run into each other again,” Ducky replies.

According to Mark Harmon, the 400th episode should be a hit with the audience.

Harmon claims he had the flashback-heavy milestone episode in mind while co-showrunner Steven Binder began writing it. This was especially true for those who had been following the show and the two characters since its inception.

“So much of what I do here is dependent on getting a script, reading it, and then attempting to approach it as a script,” Harmon told Entertainment Tonight.

“With how it ended last year for us here, four performances short, I think everybody was thrilled to come back and try to lock into what this show was and is, and what we are trying to do.”

Harmon also talked about his son Sean, who has played the younger version of his character in a half-dozen episodes since season 6. He recalls the first time they discussed casting a young Gibbs, when Sean was just out of high school. That’s when Tony Wharmby, the director, asked, “Can he come in and read?”

Mark Harmon, star of ‘NCIS,’ is pleased that his kid was a part of the historic episode.

Harmon stated that Sean walked in on his own to read for the part, and he’s glad that his son took the work seriously. The St. Elsewhere alum is especially proud of Sean’s approach to acting.

“I’m proud of both our guys, and they work hard at what they do, and I’m glad that they wake up every day and try to accomplish that,” Harmon said.

Harmon and his wife of 33 years, actress Pam Dawber, have two sons, Sean and Ty. He added that Dawber’s response to their son being photographed was motivated by her pride as a mother.

“More than anything, she’s a mother, and there’s a sense of pride in that.” Apart from everything else, as an actor, you should take joy in who people are as individuals outside of any camera, just as humans, as citizens,” Harmon explained.

He went on to say that both boys had done well and, hopefully, made wise decisions. Mark Harmon says he and Dawber have many reasons to be proud of their sons, including Sean’s appearance on NCIS.