NCIS keeps getting teased for its upcoming season as going through a major shift that viewers have never witnessed before.

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The series ended its 12th season on a shocking note back in May when a child shot Gibbs (Mark Harmon) because of a terrorist group called The Calling.

Gibbs and the rest of the NCIS team will obviously deal with this ordeal differently, but it will be a bit of a struggle.

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Michael Weatherly, who portrays Tony DiNozzo, recently spoke with TV Fanatic in West Hollywood at the CBS Television Critics Association party about the forthcoming season of NCIS, in which he revealed every two years on the series brings about change.

"Every two years, say, you go through these revolutions and when Sasha [Alexander, who portrayed Kate Todd] left at the end of Season 2, revolution. Lauren Holly [who portrayed Director Jenny Shepard] left after Season 5. Cote [de Pablo, who portrayed Ziva David] left after Season 10, big changes do require a recalibration and right now the show is undergoing kind of a metamorphosis that isn't because of anything external but more of an internal change for the first time," Weatherly explained.

Why is it "an internal change"? Well, Weatherly believes it's partly due to the fact that Gibbs was shot.

"I think there's something fundamental shifting," he said of the show coming into Season 13.

Weatherly added that the series would be putting emphasis on how Gibbs is essentially stuck in the past.

"He has no wife, no partner, he's living with all these ghosts and I get a little tired of it sometimes but the truth is I think what that message is that's really sent to the audience is that Gibbs can't move on. He's trapped," Weatherly dished.

It definitely makes for an interesting season to examine all of this stuff that has built up over the course of the series.

NCIS returns to CBS on Sept. 22 at 8 p.m. ET.

Tags: NCIS television CBS