BOOK REVIEW / BIOGRAPHY : Lost Lineage and a Man Who Won’t Talk : JACK’S LIFE: A Biography of Jack Nicholson <i> by Patrick McGilligan</i> ; W.W. Norton & Company $25, 320 pages

It’s an odd juxtaposition: A lengthy biography of actor-director-writer Jack Nicholson, published just as Vanity Fair magazine makes him its cover boy, resplendent in his wolf-man makeup and sporting a newly trim, Californians-are-immortal physique.

The book implies that most of what’s interesting about Nicholson’s life has already happened, while the magazine suggests that the best is yet to come.

And Vanity Fair addresses the one scoop that Patrick McGilligan clearly hoped would give his book “Jack’s Life” a news peg--that Nicholson was raised by his grandparents, masquerading as his parents, and that the woman he thought was his sister was, in fact, his mother.

Shades of “Chinatown,” which, in a nice coincidence, was released in 1974, the year he found out his true lineage.

So McGilligan is hobbled in the PR sweepstakes by the monthly press, which beat him to the headlines. A temporal disappointment, but not the central problem he faces. Nicholson refused to cooperate with McGilligan, and reportedly persuaded some of his intimates to keep mum, besides.

Despite the author’s yeoman efforts--he has interviewed everyone who would sit still, and read the clips on everyone who wouldn’t--the book too often reads like an account from the sidelines. The details can be fascinating, but they are observations at a distance; McGilligan gives us information but rarely makes it feel like we’re reading a life.

What’s lacking, aside from Nicholson’s own reminiscences, is a novelist’s sense of story. McGilligan has done his homework, particularly when it comes to Nicholson’s early life, but he presents it in a fairly dry fashion. Jack’s grandmother/mother, nicknamed Mud (for Mudder), made sure that Jack lived in as decent a neighborhood as her income from hairdressing would allow.

His real mother and aunt, the two women he thought were older sisters, were happy-go-lucky dreamers who kept tabs on him without letting him know exactly why (his mother died in her early 40s without ever divulging the truth, and his “sister” only confessed when a man wrote to Nicholson and identified himself as the actor’s father).

There’s some lovely detail about the young flirty Nicholson in the company of Mud’s clients--and about going to school with better-off kids whose mothers didn’t have a row of hair dryers in the house. But the material reads too much like a list; there is no resonance to the physical descriptions of the neighborhood and only intermittent glimpses of young Jack in context.

When the author has sources who like to talk, he can go on endlessly, but when he needs word from Nicholson, or from an intimate, he has to gloss over an incident. It can be a choppy read.

Which is not to say that film buffs won’t find what they do get fascinating.

The opening story, of the making of “Easy Rider,” is a funny look at how coincidence can jump-start a faltering career. The mere notion that Nicholson had knocked around Hollywood for a decade, and was nothing but a glorified kibitzer when the project got underway, is a sobering reminder that there is no such thing as an overnight star.

McGilligan has performed a useful service, as far as moviegoers are concerned--he has rounded up all extant anecdotes about Nicholson’s films and put them in one place, so that the reader can simply flip to the section of the text that talks about a favorite film and learn pretty much all there is to know.

Except, of course, what Nicholson himself has to say. There are plenty of Hollywood biographies about subjects who refuse to cooperate, but in this case the omission seems particularly glaring. Perhaps it’s because Nicholson has talked about himself so much in the past--usually to magazines, where he can get off easier than with a biographer, who’s going to demand more time and a greater level of honesty.

He’s truly one of those larger-than-life stars, who has clearly spent time trying to make sense of it all--and sometimes he has failed rather spectacularly, as evidenced by his occasional flings with drugs, weird theorists and an amusing ability to glorify serial infidelity.

This book is hardly the definitive work; it seems like a way station, halfway toward the book someone will write, someday, either when Nicholson chooses to cooperate or when mortality prevents him from asking his friends to keep quiet.