In the second episode of Season 13, at the request of Agent LeRoy Jethro Gibbs' (Mark Harmon), the NCIS team turns its attention to helping DEA Agent Luis Mitchell (John Gabriel) gain control of a drug-running case that keeps going cold.

TV Guide reports Agent Tony DiNozzo (Michael Weatherly) comes to realize Gibbs shares a tragic history with Mitchell, making Gibbs even more desperate to help in this mission.

Enthralled as team members may be in helping the agent solve the case, it soon becomes clear Mitchell doesn't have their undivided attention, as they openly gossip about Gibbs' new, far less rigid look: a modern haircut and dress shirt, as opposed to his long-customary polo and military cut.

The show's season premiere confirmed what everyone already seemed to know: namely, that Gibbs is a changed man since the end of last season, when a shooting at the hands of a young terrorist cell he previously befriended left the agent with a near-death experience.

The second episode, "Personal Day," also hints Gibbs now views the world in a completely different light, after barely surviving emergency surgery. In time, the entire experience may even make a difference in the way he performs his job as a top agent.

Showrunner Gary Glasberg recently told TV Guide that viewers this season will learn aspects of Gibbs' past previously never revealed.

"I think what we're going to have this year is a fundamental shift in the show and that's a fascinating thing to see," Weatherly previously told TV Line. "I don't want to give away too much, but I think the audience will respond with great interest to some of the tonal changes."

"NCIS" airs Tuesday, Sept. 29 at 8 p.m. ET on CBS. The series also stars Pauley Perrette as Abby Sciuto, Sean Murray as Timothy McGee, Emily Wickersham as Emily Bishop, and Rocky Carroll as Leon Vance.