Mark Harmon is set to return for the upcoming 13th season on "NCIS." Just don't expect to see the same Agent Jethro Gibbs you've become accustomed to always seeing.

"We're going to see some changes in Gibbs that are going to throw people a bit ... [Mark] is doing some fantastic work right now in just subtle nuances," executive producer Gary Glasberg recently shared with TV Line. "So, physically, you're going to see changes. Emotionally, you're going to see changes. At the end of the day, things that you wouldn't normally associate with Leroy Jethro Gibbs are going to happen."

The end of Season 12 saw Gibbs being shot multiple times by Luke Harris and clinging to life, which explains how at least the beginning of the new season will find him still struggling to adjust and away from pretty much all active duty.

With Gibbs in full recovery mode, several media outlets have reported Senior Special Agent Tony DiNozzo (Michael Weatherly) and Timothy McGee (Sean Murray) are expected to pick up much of the slack in terms of manning the field in the name of protecting the country.

Season 12 already saw DiNozzo in contact with the head of The Calling, Daniel Budd (Giles Matthey), making it all the more likely he will be looked upon as the go-to guy with Gibbs now sidelined.

"NCIS" Season 13 is set to premiere on Sept. 22, and Season 12 is now available in CBS All Access.

Before signing on for another season, Harmon recently teased the prospect of what the show might look like without him by during an appearance on "The Late Late Show with James Corden" where he explained the series "births characters leaving" during a recent guest appearance.

Later, he added, "It's not my choice, number one, but I think anybody is replaceable."