While no one was looking, a six-year-old television series that lands on few magazine covers, enjoys almost no love from critics and never gets nominated for prestigious awards is now the hottest TV show.

Yes, that title really does belong to the CBS drama NCIS. The numbers are undeniable. Last Tuesday that crime show about the Naval Criminal Investigative Service reached 18.8 million viewers, more than it ever had before and more than any other show on TV for the week.

And recently, CBS filled a weak hour, Friday at 9 p.m., with repeats of NCIS. In both weeks since, the repeat has been the most-watched show on Friday, with more than 11 million viewers each time.

The cable network USA, which added NCIS repeats to its schedule in September, have seen ratings soar anywhere they place NCIS. The show has dominated in its regular spot at 7 p.m., and on most nights it's the No. 1 or 2 entertainment show on cable, drawing audiences of more than 4 million.

NCIS repeats show at the same time on Canada's History Channel.

NCIS is part of a swing to more traditional storytelling, the kind of shows that prove to be valuable assets to their owners because they can play well over and over.

"I don't know if there's a complete swing back to closed-end storytelling," said David Stapf, president of Paramount Network Television, the studio that produces NCIS. "But those shows certainly seem to be working right now." He added, "I think what really works is the reliability if it."

Still, why would NCIS be working better than ever in its sixth season? CBS and Paramount executives pointed to a change in the show's creative leadership two years ago, when a veteran writer, Shane Brennan, took control for NCIS. Brennan came aboard after the departure of the television hitmaker Don Bellisario (Magnum P.I., JAG), who was pushed out in a conflict with the show's star, Mark Harmon.

Often that sort of rift can derail a hit series, and Stapf admitted, "I was secretly worried about it."

But Brennan is credited with breathing new life into the series. "He's given the show a sense of emotion you can really respond to," Nina Tassler, president of CBS Entertainment, said. She and Stapf mentioned a somewhat unexpected element: humour. "It's a fun show," Stapf said.

Fun? The essence of the stories is murder. But the show does emphasize the camaraderie of a quirky band of investigators. Brennan said he looked for "the naturalistic kind of humour you find in any office where people work together."

The charge from CBS and Paramount had been to "open the show up and try new things," Brennan said. He focused on what he called "the core of the show, the ensemble cast." That meant finding stories that contained memorable character moments. "The audience remembers the moments, they forget the plots," Brennan said, adding, "It's really not a procedural."

Brennan's role in the show's surge is somewhat surprising because he had never led a show before. He is a 27-year veteran of television -- in Australia. He said that gave him enormous storytelling experience because writers there work as freelancers. They must produce constantly or they don't eat.

"I have no trouble coming up with stories," Brennan said.

Tassler pointed to another move that helped kick the show into higher gear. After the writers' strike, Brennan fashioned a grabber of a cliffhanger that had the crime unit's previous boss, played by Lauren Holly, killed in a gunfight, and the new boss, played by Leon Vance, ordering the unit disbanded.

That hooked fans. And Brennan reassembled the unit this season.