From the 405, I take the Santa Monica Boulevard exit and drive east. Turning right on Rodeo Drive - always pronounced Ro-day-o - I enter a different world. The Los Angeles of strip centers, billboards, and disarray becomes orderly, clean, civilized. The sky is as blue as the topaz in the endless jewelry-shop windows, and the sun turns the white concrete brilliant, as if the whole scene were lit like a movie set, making the world's most famous street come alive. There are flowers and sculptures, and the median is festooned with Herb Ritts's and Mario Testino's "Rodeo Drive Walk of Style" photographs. The three-block-long string of shops that Martin once couldn't afford to shop at are lined up like starlets: Gucci, YSL, Ralph Lauren, and the new Rem Koolhaas-designed Prada store, an indescribably futuristic structure in which mannequins are submerged in see-through, Plexiglas-covered manholes in the floor. Everything seems familiar, because it is - from movies and television. It's practically a costar in Pretty Woman.

"That's what Beverly Hills is: a place where big companies have their flagships," Martin is saying from the speakers of my car. "There's a lot of money poured into Beverly Hills."

Every other car is a Mercedes, a BMW, or a Ferrari, and the citizenry seems divided into two groups: locals and tourists, the locals discernible by their always-open cell phones, the tourists by their openmouthed stares. There is a mind-set at work here: of being in the epicenter of something … of being "close," as Chili Palmer, the mobster-turned-movie producer in Elmore Leonard's novel Get Shorty, said. "You're close." Close to the heat, the fire, the magic of the movies...

"I view Beverly Hills, really, as about eight streets long and three streets wide," Martin says. "I'm talking about the little sort of shopping areas. It's Rodeo Drive. Wilshire. And then from Canon to Bedford or Rexford or something like that. I still don't know the names of the streets. Beverly­ Hills is very close to everything. You can get from Beverly Hills to downtown L.A. in, like, 25 minutes. It's really well located, and it's very pretty. It just has the feeling of an old-­fashioned town, even though that's a contradiction almost - an old-fashioned town, except everything is a million dollars."

But money isn't the only reason it's a different kind of old-fashioned town. From my convertible, I can hear snippets of only-in-Beverly Hills conversations.

"What's her sign? You've got to know her sign!"

"I saw her post-op, and she already looks amazing!"

"Do you have a minute for the environment?"

That last one comes from a hawker with a clipboard. He's practically leaning into the convertible, but I escape with a swift right turn. Not that I'm uninterested in the environment, but the only litter I see in Beverly Hills are the occasional Styrofoam packing peanuts strewn across the gleaming sidewalks.

"In the book Shopgirl, she [the main character, a salesgirl named Mirabelle] works in Beverly Hills at Neiman's … But she really lives in Silverlake, which is a much more modest student/artist community," Martin says. "I talk about the drive from Beverly Hills to Silverlake, which is like a Monopoly board, where you would go from very expensive to very inexpensive. It literally takes place over one street, Beverly."

Beverly Boulevard practically spans the length of L.A. But I'm not ready to go there, not yet anyway. From Rodeo, I turn right on Wilshire and pass the monolithic honor guard of megaretailing, all obediently lined along the street: first NikeTown, then Barneys New York, then Saks and, finally, Neiman Marcus Beverly Hills, the setting for much of Martin's first novel, Shopgirl, the story of a lovelorn young woman who works at the glove counter of Neiman Marcus. (The soon-to-be-released Shopgirl movie is set in Saks Beverly Hills, not Neiman's. "It wasn't that big a difference," Martin says.

But as I cruise the streets, Martin is imploring me to look deeper. Beverly Hills is more than glitz; its heart isn't a cash register. The place has a soul.

"The landmarks are now big clothing stores. I don't think of them affectionately or I just don't really notice them anymore. It's like stores changing all the time. Now it's Prada, Armani, and everything. Especially on one or two streets; those aren't my landmarks. The landmarks to me are the Beverly Wilshire Hotel, which has a beautiful, beautiful facade, and, of course, the Beverly Hills Hotel. That's from a period I call 'Hollywood heyday.' "

Since Beverly Hills has the dimensions of a small town, you can see everything in a half hour. I begin the tour, as Martin instructs, with the Beverly Hills Hotel, a pink-and-green edifice whose every inch is the essence of Southern California, and then move on to the Peninsula, in the heart of Beverly Hills. ("Very, very nice. It's a good place for tea or lunches. It's very good food, really nice.") It's next door to the I.M. Pei-designed Creative Artists Agency building. Then, on the other side of the city limits, bleeding into West Hollywood, is the Four Seasons Beverly Hills, whose lobby and bar are always a mélange of A-list actors, rap stars, and wannabes. Whether it's actually in Beverly Hills or West Hollywood is something that locals like Martin don't even know; it's of no matter. It's the Four Seasons Beverly Hills. Fiction is always much more important than facts in Beverly Hills.