Everyone remembers CSI and has probably watched an episode of the Las Vegas-based parent show or its Miami and New York spin-offs. However, there is another similarly acronym-ed procedural now in its 15th season, which has inspired two long-running spin-offs and consistently tops the American ratings for scripted shows. Yet, ask most people under the age of 50 about NCIS, and you’ll likely get a blank stare.

NCIS is one of the cornerstone shows of the CBS network in the US. A spin-off itself, born from the now-forgotten naval series JAG, the show was never initially seen as a high flyer.

During its sixth season (2008-2009), which followed the writers’ strike that led audiences to check out reruns they might have otherwise ignored, NCIS broke into the top five American shows. It has remained there consistently, even surpassing reality series American Idol and NBC’s Sunday Night Football during the 2012-13 season to claim the number one spot.

Despite regular cast changes, the show still attracts around 12 million viewers and is a significant export for the network.

NCIS stars Mark Harmon (voted People Magazine’s Sexiest Man Alive in 1986!) as the blunt, no-nonsense former Gunnery Sergeant Leroy Jethro Gibbs. He heads up a team from the Naval Criminal Investigative Service (a real organization) investigating unexplained deaths involving Navy or Marine personnel, often becoming embroiled in much wider plots.

The New York Times has described it as “meat and potatoes TV,” and even its staunchest fans wouldn’t claim it to be cutting-edge or event television like the return of Twin Peaks or a new season of Black Mirror. There is a definite “comfort food” element to it: most episodes start with a crime (usually a death) connected to the Navy, and by the end, the team has tracked down the killer. More often than not, the bad guy will be someone you’ve sort of half-noticed during the second act—they play fair with their viewers and don’t usually pull the “you wouldn’t have had a clue how to solve this” trick.

Most seasons have some form of overarching plot—there have been serial killers and terrorist cells whose actions have informed multiple episodes—and there are always a few off-the-wall episodes focusing more on the characters than the investigation.

It’s these characters that have not only got US audiences tuning into NCIS but have also made what would seem a very American-centric show a worldwide hit. At its center is Gibbs, with his many and various Rules that the team applies to situations (and his patented Gibbs slap up the back of the head for subordinates who don’t think things through properly).

He’s joined by Dr. Donald ‘Ducky’ Mallard, the British chief medical examiner played by former Man from UNCLE star David McCallum; and Pauley Perrette’s Abby Sciuto, the goth forensic scientist dedicated to the team and drinking as much Caf-Pow! caffeinated soda as she can—these three have been with the show from the start.

You can still catch reruns featuring Michael Weatherly’s Tony DiNozzo, the Riker to Gibbs’ Picard for the first 12 years, whose “will-they-won’t-they” relationship with Cote de Pablo’s Israeli agent Ziva David ended with Ziva bearing his child off-screen before she was killed off.

Completing the team is Sean Murray’s Tim McGee: the geeky one, originally the “probie” newcomer (short for “probationary special agent”), but now the trusted right-hand man.

Others have passed through—a pre-Rizzoli & Isles Sasha Alexander was killed on screen in the first of a number of such twists the show has pulled over the years. Gibbs’ early boss Jenny Shepard (Lauren Holly) also bit the dust. Robert Wagner still turns up periodically as DiNozzo’s father, a charming entrepreneur with a twinkle in his eye. Maria Bello joined the team for the 15th season, following in the footsteps of Jamie Lee Curtis in providing backup for Gibbs and co.

It’s clear from all accounts that, like his character, Mark Harmon is at the heart of the show, creating a good atmosphere on set that comes across in the finished product. Behind the scenes, there’ve been a few dramas, but Cote de Pablo’s unexpected departure at the start of the 11th year was one of the few that really affected the show in a way viewers saw.

That lack of off-screen drama and buzz may be part of the reason that NCIS doesn’t get much critical notice—it’s a well-produced hour of television that has almost become part of the furniture over the last decade and a half.

It doesn’t have a huge internet presence (Instagram and Facebook followers get a few advance clips and photos), and it doesn’t “do” politics—you’d be hard-pressed to tell the difference between a Trump-era and an Obama-era episode (although, saying that, Mrs. Obama did make a guest appearance!).

It would be doing the show and all who work on it a disservice to say that NCIS is inoffensive—but its innocuousness and clear delineation between the good guys and the bad ones are part of its undeniable charm.

It can still spring its surprises (it’s got its own resident ghost, for instance), but each season new viewers tune in for just one episode… and find themselves coming back week after week.

By chrysos