OF COURSE "The Two Jakes," the sequel to "Chinatown," had to have Jack Nicholson in it. You remember him as Jake Gittes, the private eye who dabbled with Faye-fatale Dunaway, searched for her daughter Katherine and got himself a nostril-knifing in the process.

But did the movie have to have Nicholson behind the camera? Apparently so, by default, since original director Roman Polanski's well-documented legal problems have kept him out of the country. Unfortunately, director Nicholson does not take to this case well. Even with the big-name help of cameraman Vilmos Zsigmond and a script by returnee-scenarist Robert Towne, he denies "Jakes" the assured polish a follow-up to the 1974 classic would demand. At best, the movie comes across as a competently assembled job, a wistful tribute to its former self. At worst, it's wordy, confusing and -- here's an ugly word -- boring.

Nicholson has a commanding screen presence in virtually every film he appears in. But here, just as Gittes stumbles through a murder case of bewildering proportions, actor Nicholson seems to wander lost, portly and slack-jawed through the proceedings. Nicholson also seems to have instructed his supporting performers (including Harvey Keitel, Meg Tilly, Frederic Forrest and Eli Wallach) not to upstage him. They respond accordingly and congregate around him, interjecting dialogue loaded down with names, clues and other detective-movie exposition whenever possible. There are times when the whole project ironically suggests a rehearsal for a movie entitled "The Orson Welles Story."

As for the plot: The year is 1948, 11 years after the death of Evelyn Mulwray (Dunaway). Gittes is still practicing, he's put on weight, he's into golf and he's engaged. But Evelyn's daughter, with whom Gittes has lost contact, is still at large somewhere. Undertaking a routine case for Keitel (the other Jake), Gittes overhears mention of daughter Katherine and develops more than a business interest.

Nicholson as director goes for a jokey, film-noir atmosphere. He has instructed cinematographer Zsigmond to tag along at Gittes's elbow, look over his shoulder, peer between his feet and even, on one occasion, watch the world from the bottom of a golf hole. But the strategy seems witlessly, derivatively calculated, a second-generation Dashiell Hammett world -- the kind any director can just instantly order.

The movie is no pain to sit through, especially in light of the disappointing summer season. Nicholson's performance, in spite of his constraints, still bursts intermittently through. And scriptwriter Towne (who won an Oscar for the original) reproduces, in general, the same mixture of underlying themes (real estate, mineral rights) and the above-the-surface verbal business that has always distinguished his work.

Khan, a man with information about Katherine, asks Gittes, "Are you happy?"

"Who can answer that question off the top of their head?" says Gittes.

"Anyone's who's happy," replies Khan.

But these instances are merely reminders of better times -- in "Chinatown" -- when it all came together. "Memories," Gittes says, in the requisite Chandleresque narration, "are like nitro. You never know when something's going to set them off."

Or not set them off.