The Queen of the MGM Lot : NORMA SHEARER <i> by Gavin Lambert (Knopf: $24.95; 352 pp.; 0-394-55158-3) </i>

In Billy Wilder’s film “Sunset Boulevard,” the aging Norma Desmond is a Hollywood heroine who always seems incomparable. Now we have Gavin Lambert’s “Norma Shearer,” an up-close look at the emotionally taut movie star who was queen of the MGM lot in the 1920s and ‘30s, when MGM meant something. She was married, to boot, to the studio chief and brightest man in Hollywood, Irving Thalberg. Shearer’s career was built on ladylike re-creations of great stage performances--”Romeo and Juliet,” “Marie Antoinette,” “Idiot’s Delight,” “The Women”--and although the career was over the same year as Garbo’s--1942--the lady lived on, right here in Hollywood, just like Norma Desmond.

Gavin Lambert is such a good writer that he can take a minor character, like the neurasthenic sister of the movie star, and make her an unavoidable thread in a book that has more golden threads than there are stars in Hollywood. Lambert is the English author of “Inside Daisy Clover” and “On Cukor” who understands this community as well as any historian past or present.

“Norma Shearer,” his 11th and latest book, is only apparently a biography of the largely forgotten film star. It is really more than a biography, for in it Lambert actually explains stardom and Hollywood, from the 1920s and ‘30s and beyond. Lambert knows every nuance worth knowing, and he tells all.

This is possibly the first book to unravel MGM wonder boy Irving Thalberg in a way that’s not larger than larger-than-life. Listen to Lambert nail Thalberg down in two sentences: “At the age of 22 Thalberg created a new image of the producer, as omnipotent as God, the prime mover and ultimate referee behind the scenes. He set detailed guidelines for the writer and director so that the world they created came partly out of his own head, but he took no screen credit, which earned him a reputation for modesty while satisfying a proud, secret mystique.”

Thalberg, the author discovers, could spot sublimated sex in every human relationship; he had “an objective alertness about human passions.” Lambert quotes D.H. Lawrence to reveal Thalberg--”sex-in-the-head” is the phrase--and “Sons and Lovers” was, of course, a Thalberg favorite. (No movie executive in history was as mother-centered as the frail Thalberg, whose mother ran his household even after his marriage.)

But it was Norma Shearer, queen of the MGM lot, who was Thalberg’s wife and his match. If the executive really was infatuated with actress Constance Talmadge (who didn’t love him in return), he would wind up with the steely Miss Shearer--and the fit would work. Shearer, too, had to give up her first Hollywood infatuation, director Victor Fleming, in favor of her marriage. The author suggests that Shearer-Thalberg as a couple was not a great love affair but a good real marriage of neurotic star and hypersensitive executive. Theirs was the perfect merger, and they lived the royal Hollywood life.

But Thalberg died in 1936 at age 37, and with him went a lot of Norma Shearer’s star power. When it was over for her, it was really over, and she knew it. She lived into the 1970s, but no horror pictures for Mrs. Thalberg, thank you very much. She was forever driven by demons, but not enough to give up her dignity.

What Lambert’s biography does is to give us her triumph--over everything: a malcontented childhood, a pushy mother, a cast in one eye, a not-leggy pair of legs, a mentally disturbed sister (who married director Howard Hawks), a big case of envy from Joan Crawford, and enough rejection early on to stop the most determined ambition. Lambert’s skill makes it all brand-new, this saga which provided Hollywood with the ending to all versions of “A Star Is Born.” When the heroine of that film says, “Hello, everybody, this is Mrs. Norman Maine,” that came directly from Norma Shearer, who always behaved like Mrs. Irving Thalberg, although she outlived him by several decades in a town with a notoriously short memory.

When Lambert met his subject in 1973 at her home in Beverly Hills, then at dinner at Trader Vic’s (of all the perfectly lit Hollywood spots!), and later at a screening of “Idiot’s Delight” at her former fiefdom, MGM, he met the real thing.

What had “attracted and mystified” the author about Shearer was her lack of a star’s personal image and her ability to immerse herself in a character. But in person, she was the epitome of the temperamental star, even decades after her constellation had faded. The woman who played Marie Antoinette and Juliet (opposite Leslie Howard’s Romeo), and the leader of the pack in Clare Booth Luce’s “The Women,” had the same nervous intensity in person that she had on screen.

It was touch-and-go whether the meeting would take place at all, Lambert reports. Shearer was perennially movie-star late, and the biographer had been warned that she might not show at all; but in fact, she swept in a mere 30 minutes after the appointed time. (Janet Leigh, whom Shearer “discovered,” remembers being invited to the actress’ home for dinner one evening; Mrs. Thalberg arrived hours after her guests, making a grand entrance indeed.)

But if Shearer was second only to Garbo at MGM as female star, in her personal life she was also very much a woman of her time: no scandal, not even one divorce. Her second marriage--to a younger man, ski instructor Marti Arrouge--was by all accounts happy. Together they walked all over Beverly Hills, “discovering” Robert Evans by the pool at the Beverly Hills Hotel. It was Shearer who suggested that Evans play Thalberg in “Man of a Thousand Faces,” his debut as an actor.

The author captures not only the headiness of the early years (he goes inside the Shearer beach house, which was built, as F. Scott Fitzgerald had put it, “for the great emotional moments”), but he got close enough in his interviews with the aging actress to get the small, telling moments. After their private viewing of “Idiot’s Delight,” one of the classic Broadway roles of which she made a film success, Shearer took Lambert’s wrist, “seized it with an enormously powerful grip,” and told him: “That really took me back, a long way back.”

On another occasion, at her house in town, the author quoted Fitzgerald to the actress (Fitzgerald based his short story, “Crazy Sunday,” in part on Thalberg and Shearer). “ ‘The golden bowl was broken,’ ” Lambert told her, “ ‘but at least it was golden.’ ”

The author reports that the actress caught her breath and gave him a long, unnerving stare.

That’s just what the reader wants to do, too, after reading Lambert’s book: stare at him in awe for knowing so much about the real women and men of Hollywood. Finally he has found a real-life heroine as wonderful--and scared--as his Daisy Clover. Now if only Natalie Wood were alive to play her.