Mark Harmon by Cliff Lipson/CBS; Ralph Waite by Jim Spellman/ Mark Harmon by Cliff Lipson/CBS; Ralph Waite by Jim Spellman/

This season, NCIS will do something it has rarely done: Tell us a little something about Leroy Jethro's background. has learned exclusively that in the Oct. 14 episode, when a pair of Marines are ambushed, the NCIS team's investigation leads them to no less than Gibbs' hometown. There, viewers will meet Gibbs' father - played by guest-star Ralph Waite ( The Waltons, Cool Hand Luke) - as well as learn secrets about the enigmatic special agent.

"Taking Gibbs [played by Mark Harmon] back to his roots was something we've talked about doing for some time," executive producer Shane Brennan tells us. "It was an easy creative decision to make, but a challenging story to tell."

The writers of the hit CBS drama, of course, met the challenge, and are excited to serve up a precious glimpse into their lead character's origins. "The episode is a little piece of magic, with revelations about how Gibbs grew into the man we all admire and respect," says Brennan. "It is a funny, revealing and emotionally powerful story that I think fans of the show will talk about for the rest of the season. Prepare to get choked up."

NCIS' sixth season premiered this Tuesday night. - Matt Mitovich

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