Mark Harmon, who created the role of Gibbs on NCIS, is an executive producer on the prequel—as well as a narrator—and was part of the casting process that resulted in Stowell landing the role. But when it comes to offering advice on playing the character, he’s pretty much hands off.

The origin story of Leroy Jethro Gibbs has finally begun: CBS kicked off its much-anticipated prequel Monday from veteran NCIS writers-producers Gina Lucita Monreal and David J. North, as well as CBS Studios. And as promised, Mark Harmon returned to both narrate and to appear fireside as he journals about his life.