DENZEL GIVES LESSONS IN HOW TO STOP THE SHOW.

Byline: Bob Strauss Film Critic

Denzel Washington has a good, good, good time playing a very bad, bad, bad cop in ``Training Day.'' The cliche description for this indescribably molten performance is infectious, but unfortunately that word will have to do. It captures two key facets of the actor's work: It's as irresistibly enjoyable as the character he's playing is toxic.

``Addictive'' might work almost as well, and is perhaps a more apt term, considering that the manically manipulative, intimidating and charismatic Alonzo Harris is an undercover narcotics detective working the punctured-vein streets near downtown L.A. He's been at it for 13 years, thinks he owns the place and kind of does. But this once-dedicated do-gooder has gotten so deep inside the underworld, pushing the limits of his own criminal behavior is all that gets him high anymore. The man mainlines blurring the line.

One fine morning, nice, naive, Valley rookie Jake Hoyt (Ethan Hawke) gets into the passenger seat of Alonzo's outlandish, '78 Monte Carlo lowrider, eager to prove himself worthy of joining the legendary enforcer's elite team. Over the next, preposterously action-packed 24 hours, the kid learns a lot, all right, at the expense of a good part of his soul and, maybe, his life.

Filmed in actual precincts of Rampart (where the recent police corruption scandal obviously lent the piece a certain relevance), Imperial Courts, Crenshaw and the like, the movie offers a vision of war zone L.A. every bit as frightening and volatile as Alonzo's wheedling personality is.

The film's director, Antoine Fuqua (``The Replacement Killers,'' ``Bait''), likes to let you know that he hails from a bad neighborhood of Pittsburgh, so he's down with this kind of danger. While his music video background tends to undercut ``Training Day's'' gritty urban urgency at times (as does the well-acted but distracting cameo appearances of recording artists Macy Gray, Dr. Dre and Snoop Dogg), Fuqua indeed evokes a sense of vicious street dread that genuinely seems to come from someone who's felt it. The best proof of this is that the movie's most suspenseful sequence, in which Alonzo abandons the overmatched Jake in a kitchen full of East L.A. gangbangers, pretzels the gut despite the absence of the movie's main and overwhelming source of threat.

As for the screenplay by David Ayer - another guy who claims street cred, in his case South Central - it's certainly never dull. To a fault, in a big way, since all of the murder, mayhem, trickery and tough lessons he crams into a 24-hour period might be too much for a whole metropolitan police department to handle in a week, let alone two cops G-riding for a day. But the surreal excess of alarming incidents also lends ``Training Day'' a concentrated power, enabling it to slam home the pressure of big-city police work. We come out feeling bruised, and with some notion of how Alonzo rotted and Jake had to let go of whatever innocence a cop is permitted to have.

But the real information is imparted in the front seat of that Monte Carlo, as one messed-up mind exults in messing up the other. Washington's performance is that rarest kind of tour-de-force showboat: one so rich in range, lightning-fast mood shifts and cantilevered tiers of deception that its loudness is not just forced flash, but absolutely necessary to accommodate its many riches. For his part, Hawke never lets Washington steamroll him. In fact, with marvelous control and subtlety, the younger actor wrestles his partner's symphony of technical prowess into a vital duet. That's a feat of great work all by itself.

``TRAINING DAY''

(Rated R: violence, language, drug use)

The stars: Denzel Washington, Ethan Hawke, Scott Glenn, Cliff Curtis.

Behind the scenes: Directed by Antoine Fuqua. Written by David Ayer. Produced by Jeffrey Silver and Bobby Newmeyer. Released by Warner Bros.

Running time: Two hours, one minute.

Playing: Citywide.

Our rating: Three stars