Billy Dee Williams, Mark Harmon

Is NCIS big enough for two Leroy Jethros?

On Tuesday's episode (8/7c, CBS), we may just find out. During the hour, aptly titled "The Namesake," Gibbs (Mark Harmon) will once again cross paths with Leroy Jethro Moore (guest star Billy Dee Williams), the man after whom Gibbs was named.

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"Leroy Jethro Moore is a World War II Marine veteran who received a distinguished Medal of Honor," Williams tells TVGuide.com of his character. "I think he was one of the first to receive that honor. He's an old friend of Gibbs' father, and they have not seen each other for a long time. A particular incident brings us together and we begin to review our friendship and our lives together 30 years prior."

That incident involves the elder Leroy Jethro — thankfully nicknamed L.J. — pawning his Medal of Honor. "He basically tries to sell the Medal of Honor to pay for something that he cares about," executive producer Gary Glasberg says. "Because he's not an egotistical man, it doesn't mean anything to him. Gibbs comes across the medal, and of course it's illegal to sell a Medal of Honor. So he takes it and then ultimately gives it back to him."

For Gibbs, it's an interesting chance to reunite with a man who was a major influence on him. "L.J. was a presence in young Gibbs' life," Glasberg says. "He was a former Marine, and that certainly influenced our Leroy Jethro Gibbs to make the decision to become a Marine. This was a man he looked up to, in addition to his father. I think there's absolutely a connection and an appreciation for what L.J. did when he was younger."

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Unfortunately, the same can't be said of the relationship between L.J. and Jackson Gibbs (Ralph Waite), whose former friendship has been on the rocks for some time. "There's a story element that comes into play that sort of drove them apart," Glasberg says. "It comes from a place of [Jackson's] stubbornness. Ultimately, it's Gibbs' responsibility to get them back together again."

And in doing so, Gibbs will stumble upon some (potentially troubling) old emotions. "It's a very interesting reunion," Williams says. "They were very close friends in a very special way. It's pretty visceral, pretty deep —and very touching actually."

Adds Glasberg: "[There's] a connection to Gibbs' mom as well, and what their friendship and their relationship was all about. ... I think it definitely gives you some insight into the Gibbs psyche. Anything that we can learn about Gibbs as a child, about what his home life was like, about the people who helped raise him — I think it all adds to the understanding of who Leroy Jethro Gibbs is."

NCIS airs Tuesdays at 8/7 on CBS.