BURBANK, Calif. — Zachary Levi is embracing his inner nerd.

"I'm more Chuck than I'm not Chuck," says Levi on the set of NBC newcomer "Chuck," in which he plays a computer geek turned clueless secret agent. "Pretty much my whole life, actually, I've felt like a nerd. Growing up, I was always the best friend to the girls, never the boyfriend."

The tall, dark-haired actor admits to a fondness for Chuck's geek-chic couture — cheap pants and shirt, complete with a pocket protector that he wears for his day job as a "Nerd Herd" technician in a Buy More Electronics store.

"I love the wardrobe," Levi says. "The show is about the underdog, about the unwitting, reluctant hero. It's a Clark Kent-Superman kind of thing."

But Chuck never acquires the physical powers of a superhero on the new one-hour, action-comedy series airing on Mondays. Instead, his brain has become a priceless file of secret intelligence data since he opened an e-mail that imprinted his mind.

Besides, Chuck is a klutz at spycraft. His government watchers — humorless Maj. John Casey of the National Security Agency (Adam Baldwin) and sexy CIA agent Sarah Walker (Yvonne Strahovski) — tell Chuck to wait in the car when assassins are afoot.

"Chuck's just so innocent," Strahovski says on a recent production day on the Warner Bros. lot. "Not only does Sarah have to protect the government secrets in Chuck's head, but she also has to protect that innocence."

In between martial-arts moves, Sarah does develop a thing for Chuck as she plays out her cover story of being his girlfriend.

"Sarah has been trained not to trust anyone," Strahovski says. "But Chuck and Sarah do bond because they go through so many near-death experiences."

And Chuck's pocket-protector look? Well, Sarah "finds it adorable," Strahovski says.

On the "Chuck" set, the 27-year-old Levi seems the polar opposite of geeky. Clutching a large coffee, he's Mr. Take Charge, shepherding visitors through a faux courtyard, arranging seating and asking, "Is everybody good?"

"I was a busboy, I worked at Blockbuster, I worked at a car wash — which was character-building," Levi says. "So I can relate to the customer-service thing. Doing your best with a smile. That's what Chuck stands for."

Before "Chuck," Levi played snobby Kipp Steadman on the sitcom "Less Than Perfect" and did supporting turns in "See Jane Date," "Big Momma's House 2," and other movies. He recently produced and starred in the indie film "Spiral."

"I went from everyday scraping it out to Chuck on a show called 'Chuck,' " Levi says. "Getting this show was like Chuck getting government secrets implanted in his brain. You just kind of fear it and embrace it."

Created by executive producer Josh Schwartz ("Gossip Girl," "The O.C.") and co-executive producer Chris Fedak, "Chuck" is rooted in twentysomething angst.

Expelled from Stanford for murky reasons, Chuck is having what Schwartz, Fedak and executive producer McG call a "quarterlife crisis."

"From the get go, Josh and I talked about a mashup of ideas, a fusion of a character-based comedy and hard-core action," says Fedak, an action-movie maven who was Schwartz's film school buddy at the University of Southern California.

Indeed, on "Chuck," the scheming workers of big-box Buy More seem as menacing as the secret-agent types.

"The notion was, what if Sydney Bristow on 'Alias' or Jack Bauer on '24' wandered into 'The Office'?" Fedak says. "How terrifying that would be, because Sydney's friends and family all usually got killed. And Jack Bauer usually wants to torture somebody."

Casting Levi in the split-personality series was a no-brainer, Fedak says. "At his first audition, Zach sat there for a second and then he went, 'OK, don't screw this up,' and he went into his audition. That 'don't screw this up' was pure Chuck."