It’s L.A. in the late ’40s. A squad of head-busting cops, given a mandate to drive organized crime out of town, have come up against a case that puts them up against the powerful Atomic Energy Commission and the FBI.

That’s the basic story of Mulholland Falls, a neo-film noir thriller starring Nick Nolte and directed by a phenom from New Zealand, Lee Tamahori.

Nick Nolte stars as Lt. Max Hoover, the leader of the elite police detectives, based on the infamous Hat Squad of the late 1940s. The squad had a blank check to force organized crime out of L.A. and keep it out, and it operated well outside the law (remember, this was before suspects were considered to have any real legal protection). Chazz Palminteri, Chris Penn and Michael Madsen round out the squad; they were all impeccably dressed and collectively weighing half a ton.

They find the smashed body of Allison Pond (Jennifer Connelly) at a suburban construction site. The police soon receive a film, which not only shows Pond cavorting with General Timms (John Malkovich), but also some disturbing scenes from the Nevada nuclear test site. But there’s more; Hoover has had an affair with Pond, and he takes the case rather personally.

Naturally, the squad follows the case and gets in way over its collective head. The plot takes some time to build, but once Nolte’s guys sneak into the base and get a look at an a-bomb crater, the plot jacks up a notch.

Mulholland Falls has all the makings of a ’40s-style noir cop movie: brutal cops, ruthless bad guys, dames, blackmail, booze, smokes — and a bit of Cold War intrigue. It is also violent, not throughout but in intense bursts, usually when Hoover cuts loose with a blackjack on someone he doesn’t much like.

The cast is exceptionally strong, with excellent supporting turns from Melanie Griffith, Treat Williams and the always bizarre Bruce Dern, who has a short but memorable cameo as the L.A. police chief.

It also looks great — dark, smoky, mysterious and dangerous. Tamahori should be a force in Hollywood, if he gets the right scripts.

Sounds great, eh? But Mulholland Falls is not great, merely acceptable and competent. With all the great style and actors, it just doesn’t go anywhere. It has difficulty sustaining interest, and the film just sort of wheezes and gives up at the end, which is foreshadowed as being apocalyptic but is nothing of the sort.

Overall, it’s just sort of OK. Check this one out at the one-buck-and-a-floor-full-of-gum theaters once it’s finished at the first-run houses.