Ellroy's novel starts off as a masterpiece of atmosphere, tough dialogue, and lurid detail that after several hundred pages sinks under the weight of its implausible overplotting. This razor-sharp adaptation retains most of the good stuff while masterfully untangling, compressing and realigning the bad. Set in a lushly re-created 1950s Hollywood shot in the overripe colors of a trashy celebrity magazine cover, the film opens with a sequence that falls into the plus ça change category. It's Christmas Eve in a downtown station house, and fueled by booze and escalating rumors, the officers on duty beat the crap out of some Hispanic prisoners accused of assaulting a pair of policemen. The headlines the next morning scream "Bloody Christmas," and the department, eager to keep up its good image after putting mob kingpin Mickey Cohen away on tax-evasion charges, decides to look for a scapegoat.

Enter Sergeant Ed Exley (Guy Pearce outstanding in a complex, seemingly unsympathetic role), the hapless officer in charge during the incident. A brown-nosing opportunist and pencil-necked geek ("Get rid of the glasses" is his superiors' unheeded advice), Exley is already hated by his colleagues, so he enthusiastically turns them in in exchange for a promotion. Among those disciplined are Sergeant Bud White (a beefy and brush-cut Russell Crowe in a crisp Jack Webb likeness), a brutish shoot-first-and-ask-questions-later type with a thing for wife beaters, and "Hollywood Jack" Vincennes (a suavely cynical Kevin Spacey, whose light touch gives L.A. much of its oomph), a "celebrity cop" who serves as technical adviser to a Dragnet-like TV show -- when he's not setting up dope and sex busts of movie stars for scandal-sheet editor Sid Hudgens (Danny DeVito doing gleeful smarm). Vincennes shakes the rap off, White vows revenge.

Each gets a chance at redemption after the "Nite Owl Massacre," a mass murder in a diner that Exley succeeds in pinning on a trio of "Negro" teens (the film, like the book, is faithful to the non-PC attitudes of the time). Exley subsequently blows the kids away during a botched escape attempt. But something doesn't sit right, and so, at first independently, the three seek the truth in a cesspool of corruption, murder, and vice. Deep in the muck are jaded millionaire and entrepreneur Pierce Patchett (David Strathairn), and looming over it all is enigmatic head of detectives Dudley Smith (James Cromwell, much removed from his role in Babe), whose Old Sod blarney conceals a ruthless canniness and unyielding ambition.

Although the film's streamlining of the original material allows the multilayered narrative to surge ahead, some sacrifices have been made. One is the women -- though not a big presence in the book, they're practically nonexistent here. As a high-priced call girl made out to be a Veronica Lake look-alike, Kim Basinger looks like Kim Basinger; her love scenes with Crowe lack steam, and one with another character is downright silly. Also, the motivations and backgrounds of the three heroes have been purged of layers of funky complication; in the end each finds as his inspiration the naive and unconvincing desire to return to whatever decent impulse got him to join the police force in the first place. So much for the festering noirish conventions of secret scandalous pasts, substance addictions, and twisted sexual tastes.

But if the conversions are simplistic and glib, the bonding and consequent bloodshed that follow are rousing and superbly executed, with a climactic shootout that's one of the most ingenious and jolting of its kind. Although the film loses some pizzazz after Spacey, invoking perhaps the spirit of Keyser Soze, utters the name "Rollo Tomassi" in one of the more shocking plot twists, Confidential remains a glitzy tribute and a full-blooded reinvention of a venerable tradition.