Mugged by sheets and pillow slips

Some facts about Baby Blue Tyler, the Hollywood heroine of John Gregory Dunne's new novel: her real name was Melba Mae Toolate - or perhaps Myrna Marie Toolate, it's hard to be sure. She was born in San Bernardino, California - or maybe Yuma, Arizona. Or possibly Shoshone, California. There's a choice of dates, too. As the narrator, Jack Broderick, says: "That's exactly how it happened. More or less."

Some facts about John Gregory Dunne which may be thought exact, more or less. He is the author of several novels including The Red, White and Blue and Harp, and of The Studio, a report on the workings of Twentieth Century Fox, published in 1969, one of the seminal works of the New Journalism; his brother is the writer and film producer Dominick Dunne; he is married to the writer Joan Didion; they live in New York; and his new novel is a cracker, attesting, one hopes and assumes, to its author's fully recovered health (Dunne collapsed at the end of 1992 and underwent heart surgery to clear a blocked aortic valve).

At the centre of Playland is Broderick, the sour-tongued, disenchanted screen-writer ("my father had the manners of a billy club and the tact of a fart; abuse was his natural dialect, his way of keeping trim" etc). Stories seem to happen to him. There's a short and beautifully set-up sequence in which, on a quiet New York side-street, Broderick sees a woman having her bag snatched and intervenes, clouting the assailant in the face with a carrier bag containing "$331 worth of sheets and pillow slips". The assailant goes down ("his brain was so rotted with crack and smack and booze") but, rather than staying to thank her saviour, the woman retrieves her bag and runs away. "I was just left standing there, no victim, no bag, and this spade Stevie Wonder clone is lying on the sidewalk with blood coming out of his ears." Broderick is promptly hauled in by the cops under suspicion of a racist mugging and undergoes a tersely written police interrogation. You're 36 pages in at this point and hooked.

Broderick goes to Detroit to hang out with a detective called Maury Ahearne to tease out material for a high-concept, short-homicide-cop-with-tall- sidekick screenplay. It is partly the book's intention to send up Hollywood, where Dunne lived and worked for 24 years to 1988 - to laugh loud at its ridiculousness and take a smack at its self-enclosure and at the imposters who remake themselves there. Broderick says: "I hear that film is truth at 24 frames a second, Godard's formulation, and I want to grab an AK- 47 and spray the room."

Some incidents don't seem far removed from recent Hollywood history - the case of Chesty Warren, for instance, a stuntman, killed in "an elaborate and unnecessarily dangerous helicopter gag" on the set of a movie being made by "top-seeded shit Sydney Allen". Occasionally Dunne even permits himself a jokey wave to his friends: "[on TV] Pauline Kael talked about the dark and perverted sexuality of Blue Tyler's film presence; she was the only one on the show who made any sense." But the book is still intrigued by the film world's processes and possibilities, so the pervasive tone is a sort of enthralled scepticism.

Broderick soon happens on a better story than the cops with a height problem, running across Blue Tyler, missing some forty years and presumed dead. Tyler is a vibrant, brassy creation, Shirley Temple with a foul mouth. At the height of her fame, we find her at a press conference, shepherded by studio promotions people and asked from the floor about her hobbies. "Drowning cats." she says. She falls in with the mob, in the form of the Las Vegas-loving, hotel-building Jacob King (Vegas, like Hollywood, is pictured here as a sealed place in which extravagant fantasies of self go unchecked) and then drops out of sight. When Broderick comes upon her, in 1991, Tyler is living in a trailer park, a crabby bag lady, shopping with money-off coupons in the local supermarket, and Broderick is pricked to piece together those missing years.

He's sent back through a mountain of tapes, movie magazine stories, press clippings, court reports - a welter of warring statements and separate versions of the truth. Its preoccupation with murder and with Hollywood in the Forties sets Playland in the same ill-lit and alluring zone occupied by Dunne's True Confessions, published in 1977. (Dunne and Joan Didion wrote the screenplay for the movie.) Tom Spellacy, the detective from that book - Robert Duvall in the film - strolls casually into Playland when Broderick turns him up in a database search.

When the central pre-occupation is self-invention, where do you look, the novel wonders, for proof? But the counter-thesis is built in. At one point, we see Broderick replay the death in a car accident of his wife Lizzie, dropping into the third person in order to see himself - as if from above - identifying her corpse in the morgue, revolving the scene's possibilities as screenplay. These pages feel at once shocking and tender: shocking because it seems so chillingly professional of Broderick to be framing this event up in this way; tender because doing so is really his only opportunity to get outside the event and make any kind of sense of it. This novel, so thoughtful about the inefficiency of narratives of so many types, is, at the same time, an affirmation of reasons why one might need fictions in the first place.