For more than two decades, NCIS has been one of the most familiar sights on American television.

Characters have come and gone, beloved agents have said goodbye, and the team has changed dramatically since Mark Harmon first stepped into the role of Leroy Jethro Gibbs.

But somehow, NCIS keeps moving forward.

Now another chapter is approaching as CBS prepares the franchise for its fall return.

The original NCIS remains at the center of the universe, with Gary Cole’s Alden Parker leading the team alongside familiar faces including Sean Murray’s Timothy McGee, Wilmer Valderrama’s Nick Torres, Katrina Law’s Jessica Knight and Brian Dietzen’s Jimmy Palmer.

For longtime viewers, however, the franchise has become about much more than one Washington team.

NCIS: Origins has allowed fans to revisit a younger Gibbs and the world that shaped the character long before the original series began. Mark Harmon has remained connected to that story behind the scenes, giving longtime Gibbs fans another link to the show’s earliest years.

That’s what makes this next fall season particularly interesting.

More than 20 years after audiences first met Gibbs, DiNozzo, Abby, Ducky and the original team, NCIS has managed to become something few television dramas ever achieve: a multi-generation franchise.

The faces may change.

The cases may change.

But millions of viewers still recognize those four letters immediately:

NCIS.

And as another fall season approaches, longtime fans will once again be watching closely to see where the story goes next — and whether the franchise still has a few surprises waiting for them.