The creators of NCIS: Origins explain Mark Harmon’s involvement in the prequel series. The premiere of the CBS series is mere weeks away, focusing on a younger version of Leroy Jethro Gibbs (played by Austin Stowell) in the early 1990s. But the NCIS spinoff, which is executive produced by Harmon, will be narrated by the actor and he’ll also make an on-screen appearance.
