Mark Harmon and NCIS: Origins Star Austin Stowell Go Inside the Prequel Series: 'We're a Family Already' (Exclusive)

When Mark Harmon first read the guest role of Naval Criminal Investigative Service special agent Leroy Jethro Gibbs on JAG in 2003, one thing stood out immediately.

"The name caught me," Harmon, who couldn't have known then what a TV mainstay Gibbs would become, tells PEOPLE. 

NCIS, on which Harmon starred for 19 seasons until 2021, remains one of TV's most popular crime franchises. It also hit its 1,000th episode this April and has spawned four spinoffs.

Now, a fifth, NCIS: Origins, set in 1991, follows young Gibbs. 

"It's an NCIS-verse you haven't seen before," says Austin Stowell, 39, who inherits the character. Harmon, executive producing and narrating the new series — and appearing in its debut episode on Oct. 14 on CBS — agrees. “We're not trying to do something over again.”

For Stowell, leading a highly anticipated network prequel is “the opportunity of a lifetime.” Watching the two-part premiere, he tells PEOPLE, proved emotional. “I was a mess at the end of it.”

To breathe new life into an iconic character, Stowell “had to become Gibbs’ biggest fan,” he adds. Luckily, in Harmon, he had a mentor with a lot of experience. Ahead of the Monday, Oct. 14 premiere, PEOPLE caught up with the duo for a sneak peek at NCIS: Origins.

PEOPLE: Mark, what do you remember about casting Austin as a 1991-era Leroy Jethro Gibbs?
HARMON: I felt the room jump a little when Austin came in, before he said anything. He walked out and someone said, “I'll just say it, that's a movie star.” And there was heavy competition there. There were a lot of good [actors in contention]. 

Austin, what about your introduction to your character? 
STOWELL: If I can start imagining myself as [a character], in their shoes, then I know it's working. I read the first episode, and right away there were lots of parallels to my life. I knew the show, I knew the character — not as intimately as I do now — but just as I started to turn the pages, I had these moments over and over again, saying, “Oh, I know this guy.”

So how did you go about approaching playing a younger version of Gibbs, this icon Mark brought to life?
STOWELL: I knew I had something that I could bring to the character that was very real, that was palpable. But I also knew that I was stepping into a character that was creative, created and filled out and beloved by this guy for 20 years. And I wanted to pay homage to his acting talent. So I wasn't doing an impression, but I was trying to encapsulate who I thought Mark was. And I do that every day now. He leads by example. We're all here because of him. I think about him constantly. [To Harmon] I dream about you. Which is —
HARMON: A little frightening!
STOWELL: I dream about the show, almost every night. He's given me the greatest gift that I could ask for… This is the Gibbs who's making mistakes, who's living with ghosts and trying to put his life back together. And that's a lot of fun for me to play.
HARMON: Austin has to birth this guy. He's got the challenge and also the gift to be able to play this guy younger and to be able to let him be the newbie.

Talk about balancing making a different show with inheriting such a beloved TV franchise. How are you thinking about its legacy?
STOWELL: What the mothership [NCIS] did so well was create this feeling of family. Like you knew the characters that you were inviting into your home. And I think that's a big difference between films and television, especially episodic television like this. You choose to turn on the TV when you have your intimate moments with your family. It's time when you're cooking dinner, it's time when you're relaxing after a day of work, sitting on the sofa with your loved ones. That is a big responsibility for a show like this.

Does that ever feel daunting? 
STOWELL: No, it's not. It only means I have to come to that level. And that's okay with me. I like reaching for a bar that's higher, that fuels me when I get out of bed in the morning. The fact that I know that there's 300 million people out there who are waiting to see what this is only makes me fight harder and make me want to fulfill their expectations.
HARMON: He's got his eye on the ball. In some ways, it gets bigger every day, the responsibility of it. But right now he's just trying to make the work be the best it can be every day. That's got really nothing to do with what you do in acting class. It's got more to do with who you are as a human being.
STOWELL: I got to be writing all this down! This is another part of the value that Mark brings to the table is that he comes and talks to all of us… Immediately, I store all that in my head. I've never been on a show like this. I've never been a [number one on the call sheet] before. This is all brand new to me. So he comes to offer that kind of advice and that immediately, I store all that in my head. 

What is the Origins shooting schedule like? 
HARMON: They're working long hours right now. They're working night hours. It's all part of it.
STOWELL: You're going to work every day. I wake up, I train, learn my lines, go to set. Wash, rinse, repeat, Monday through Friday.
HARMON: And you get questions like, "Well, how do you handle that?"
STOWELL: You just do.

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What is your favorite thing about creating this new show?
STOWELL: We've all worked really hard at this and we're trying to get it right. It looks beautiful. I [am] just really happy for all of our crew, that it's going to be something that we're all going to be proud of... I've gotten to know them, so many, really intimately, I know about their kids and their plans for the weekends. It's not lost on me that a big part of that responsibility is to keep everybody at work. I like that responsibility. It gives me great purpose. I don't just go to work for me, I go to work with everyone… I've been able to concentrate on what I need to concentrate on because I do feel like I have a safety net.
HARMON: When I was selling shoes, I used to always look at my watch and I'd go, "Lost four hours today. Where are we going to make that up?" Guess what? At a certain point you stop looking at your watch. Maybe sleep is a little overrated. You care about your crew… You walk on the set, you can feel it.
STOWELL: We're a family already.
HARMON: And if you can bring that to it too, what Austin's talking about, then you venture into the territory of something special and it becoming a little more than a job. This is a place where everybody's busting their tail because they want it to be good. It’s not about a paycheck.

NCIS: Origins premieres Monday, Oct. 14 at 9 p.m. ET on CBS. Episodes will also stream on Paramount+.