"Brookie" cannot possibly go to the taping of the Johnny Carson show in THAT limousine. THAT limousine doesn't even have blackout windows. People would be able to look right in and see her as she was driven into the NBC studios.

So the limousine driver has to return to headquarters for a limousine with blackout windows. And in THIS limo he transports Brookd Shields, who turned 13 a mere twinkly ago, to her guest appearance on the "Tonight" show.

Later, Brooke, whose starring role in Louis Malle's film "Pretty Baby" has made her the youngest sex goddess in movie history, is whisked back to the set for the last few hours of shooting on her latest film, "Wanda Nevada." She plays the title role, costarring with Peter Fonda, who has directed the picture.

"I cast her before I saw 'Pretty Baby,'" says Fonda, who sports a borderline mustache for his role as a gambler. "I wasn't very impressed with that film, but it wouldn't have changed my mind about using Brooke."

Fonda wins Wanda in a card game, according to the script, and takes her off on a search for gold that leads them to the Grand Canyon, described in a press release as "the greatest canyon of them all." Brooke is not playing anything similar to the child prostitute of "Pretty Baby." Wanda Nevada is a young runaway from an orphanage. Still. . . .

"The nuns want her back," says Fonda, explaining the plot and fighting a stomachache. "And Seven Darden plays a dirty old man who wants to go to bed with her. The guy I play is very mean to her - I throw her around, and kick her around a lot - but I'm the only one who is true to her."

"I wear all this red lipstick," says Brooke, sitting on a stool as her hair is brushed by an assistant for at least the 12th time. "But the girl I play is not all blown up. She does little things that give her away. I do fall in love with Peter, but like a dad, you know? I try to act all womanly and everything and that's where the innocence comes in."

Fonda says the film is about "innocence."

Brooke says the film is about "innocence."

Innocence could not be reached for comment.

Brooke Shields was discovered by the camera at the age of 11 months. She has been in front of professional photographers constantly ever since. In "The Brooke Book," published by Simon and Schuster and sold out at several Hollywood book stores, Brooke can be seen sleeping in bed, lounging in the bathtub, and made up to look liike a wide variety of women of th world.

She has also appeared prominently in the pages of Penthouse magazine.

Asked if, considering all this, she has been able to retain any innocence herself, she answers officiously, "I try to yes."

Brooke is not you typical all-American child star. She is no living dimple like Shirley Temple nor has she gone the tomboy and glitter rout of Tatum O'Neal. Seh is an accomplished actress with a photographic memory which rarely fails her in remembering dialogue, but what makes her for better or worse a figure of her time is that precocious trace of femme fatale . She is an appropriate icon for an age that worships appearance.

On stage four of what used to be the Selznick studios in Culver City, a few blocks from MGM, where "Wanda Nevada" is being wrapped up> Brooke is almost always in the company of two or three friends, one of them Fonda's daughter Bridget, 14, who has the long blond, straight hair of a '60s folk singer. A woman identifying herself as Brooke's godmother, Lyla Wisdom, is also there, as are two tutors - one just for foreign languages - and, in something beyond full bloom, Broooke's mother, Teri a bubbly, zaftig woman who makes an entrance on this last of shooting by falling to her knees and doing a series of elaborate Kowtows.

Soon, like others on the set, she is wielding a can of Coors. She talks very loudly and with grandiose gestures, hugs people, kisses people, dances about and laughs broadly.

"It's embarrassing," murmurs a member of the production team. "Sometimes she makes terrible scenes." No one else wants to talk about that.

"My mother used to be a model," Brocke says. Oh, not real modeling Someone would just say to her. 'Hey, Teri, try on a coat,' and she would." (Her father, divorced, is Revlon executive Frank Shields.)

Brooke gives the appearance of having made all afjustments to ther quixotic, cushy enviroment with her sanity if not her innocence intact. Perhaps success hasn't spoiled her because success is all she has ever known.

"Brooke doesn't think she's a big deal and never does anyone give her the idea that she is," says Wisdom. "People come and go in this business and she's the first to understand that. Pretty girls are a dime a dozen and she knows it."

"OW!" shouts Brooke. She frowns at the woman brushing her hair. "Sorry," says the woman, and the brushing continues.

"A lot of people try to find a lot of things wrong with me," Brooke says without rancor. "Mostly they just pick out specific mistakes that I made. Like once it was very late at night and I was talking to someone and I was very tired and then they wrote about how I was 'slouched' down in my chair. Well I do have a bad posture, but everybody's gotta slouch sometime!

"I have bad grammar sometimes, too."

David Hartman, America's self-annointed high priest of normalcy, interviewed Brooke on ABC's "Good Morning America," and then, when she had left the studio, complained on the air that "pretty Baby," the movie he'd just helped promote, was exploiting a child.

"Oh, I don't remember anything about that," says Brooke, who saw "Pretty Baby" four times. "Anybody can really say what they want. I'm not worried about it anymore."

It has taken about 10 weeks to film "Wanda Nevada," scheduled for release next year. The actors and crew work late into the night but this is not hte hard part. The hard part is spending two weeks on the floor of th greatest canyon of them all where the temperature once reached 140 degrees.

"We had five people bitten by scorpions," recalls cinematographer Michael Butler."I woke up one morning and found one in the sink, so you knew that they'd been crawling all over the place at night."

"Oh, it was fun," says Brooke.

"Brooke bore up better than most," Fonda says of the Grand Canyon shooting. She was less concerned with dodging the scorpions than with meeting Fonda's father, Henry, who plays an old geezer. "Wanda Nevada" marks the first time Peter has directed Henry in a film.

"I told him, 'Dad, I can only pay you $1,000 for an honest day's work,'" Fonda says. "Brooke came running over to me on the set one day, shouting 'Look, I got his autograph!'"

Brooke also got Johnny Carson's autograph the night she appeared on his program. "I liked him," she said, after taping the show. Carson's teen-age son had sent her a note saying he wants to meet her someday. Johnny himself gave it to her.

But back on the set Brooke complains to her friends that she didn't get enough time on the air to talk about the movie."I was ready to talk about it real fast, bleh-bleh-bleh-bleh-bleh," she tells her friends. "And he said, 'We'll be right back after this commercial,' and then he says, 'Thank you Brooke for being here.'" She holds up her arms in a gesture of exasperation.

Then she notices a friend's silver silk blouse, feels the material, and bestows a generous, "I like that." Brooke can soon be seen eating chips from a bag of Ruffles and drinking a 7-UP. Pauses between shooting scenes can be, nearly interminable. "I play around with my friends" to kill the time, Brooke says, "or I get into trouble. Anything that's available."

Sometimes she will pout. "Oh, I don't want to do reshoots," Brooke confesses, but she has few other complaints about making movies. "My mother reads the scipts they send us and if they're real dumb or boring or something she just sends them back. If she likes them, then I read them. I'm enjoying it so far. But I do know that even if I keep acting I want to be a mother when I grow up."

When Fonda finally says, "I think Brooke's finished on camera," she bursts out the soundstage door shouting an ecstatic, "I'M LEAVING!"

Right outside, a portable TV set has been placed on the hood of a parked station wagon so the company can watch Brooke on the Carson show. Brooke has changed from her movie costume - jeans and a gingham shirt - into a satin jump suit with the name "The Hollywood Reporter" on the back. Then she runs off to her trailer and changes back into the jeans. Then she runs back to the trailer and changes back into the suit. It really doesn't matter since she always looks perfect.

A crowd has assembled around the station wagon. "I want to watch the funny part where he goes 'pyew, pyew,'" says Brooke. She is talking about comic Charlie Callas, another guest on the program. Last year's sex symbol, Farrah Fawcett-Mayors, is on the show, too. She and Brooke exchanged autographs backstage. The torch is passed to a new generation.

America's taste in sex symbolism gets younger.

Brooke is very animated while watching the program. She laughs. She giggles. She nudges her friends. But when it is time to watch herself, she turns instantly contemplative, quiet and almost sullen. Occassionally she lapses into that gaze of fearful vulnerability that has obsessed some of the world's greatest photographers. Or her imposing eyebrows will lower and her bottom lip extend into something of a stylish and provocative pout.

No matter what expression she assumes, she always looks uncannily exquisite, and when a hired photographer begins snappking photos of her and a syrobe bursts repeatedly in the Hollywood night she never even blinks.

Inside, on the soundstage, as a rowdy and affectionate parting gesture, the crew is pummeling and pelting Fonda with whipped-cream pies.

There will be no such pies for Brooke.