NCIS: ORIGINS premiered this week, and in honor of the show, stars Mark Harmon and Austin Stowell spoke to PEOPLE about their roles.

Mark Harmon has opened up about casting Austin Stowell as the younger version of Leroy Jethro Gibbs in NCIS: Origins.

In the role of former NCIS lead Leroy Jethro Gibbs, Mark Harmon is a tough act to follow. But it seems he found a worthy successor in NCIS: Origins star Austin Stowell.

NCIS: Origins has premiered on CBS, and Mark Harmon’s role in the first episode has been revealed. It was previously reported that Harmon, who serves as executive producer and narrator on the NCIS prequel,

Mark Harmon transitions from his iconic role as Leroy Jethro Gibbs to executive producer and narrator of "NCIS: Origins," a prequel exploring his character's early years.

It was just an unexpected surge of emotion for us both,' co-showrunner Gina Lucita Monreal says of seeing Harmon dressed as Gibbs again.

Even the "NCIS" origin story for Austin Stowell has a Cracker Jack opening. The impossibly rugged actor, 39, had tried to clear his mind after his February audition for "NCIS: Origins," the prequel series to the CBS police procedural (premiering Monday,

Origins series premiere was a fun surprise for long-time NCIS fans. The new prequel show aired its first two episodes on October 14, and the franchise took a new direction. NCIS: Origins is set in 1991 and will tell stories about young Leroy Jethro Gibbs and young Mike Franks.

Mark Harmon recalls Gibbs actor Austin Stowell's audition for NCIS: Origins, revealing when he knew the actor would be perfect for the role.