'The Departed' (R) (out of four)

If those Oscar voters who've held out on director Martin Scorsese all these years are looking for that film that will justify a statuette, then "The Departed" may finally be the ticket. It's as close as it comes to the films that he should have won for years ago -- a compelling film that stands on its own, rather than being the basis of a "body of work" consolation prize.

A brutal crime opus that maintains its steam for nearly all of its two-hour-30 minute runtime, "The Departed," for the most part, lives up to its hype. It's energetic, briskly edited and of course, infuses classic rock tunes to help drive the film forward.

Most importantly, it's populated with believable characters that, yes, get the Bawstin accent right. And that's an absolute necessity when it comes to delivering screenwriter William Monahan's razor-sharp dialogue that slices and dices all things politically correct (the F-bombs and slurs against race and sexual orientation are flying fast and furious). Screwing up the dialect could have made "The Departed" a caricature of mob movies. But instead, it's a raw portrayal of street life at its ugliest.

Last, but not least, the "The Departed" wouldn't truly be a Scorsese movie if it weren't for its unrelenting violence -- but like before, it's the sort of bloodbath that actually serves the narrative. It's part of the reason the filmmaker is such a master storyteller.

An American adaptation of the 2002 Chinese crime drama "Infernal Affairs," the Hong Kong setting is swapped for the mean streets of South Boston. Leonardo DiCaprio -- back in his third consecutive Scorsese picture -- stars as William Costigan, an undercover cop for the Massachusetts State Police who's assigned to infiltrate the city's crime underworld, run by notorious Irish-American mobster Frank Costello (Jack Nicholson).

On the flipside is Colin Sullivan (Matt Damon) a state police rookie on the fast track to the upper ranks of the department's Special Investigation Unit. But there's a reason for Sullivan's sudden success: Since boyhood he's been groomed by Costello to eventually become the mob's mole inside the police department. So, thanks to tips from the big man, Sullivan's conveniently been in the right place at the right time enough to give the appearance that he has the makings of a top cop.

Although the story is far more complex than this description suggests, "The Departed" at its heart is about how the two men teeter on the edge of their sanity while living their dual identities -- knowing very well that a brutal fate awaits them if their cover is blown. As the movie rolls on, it becomes increasingly clear to cops and the thugs that there are rats in the mix -- and the cats in this cat and mouse -- make that rat game -- are starving for blood.

Not surprisingly, Nicholson is brilliant as Costello. He plays the world-weary killer/drug dealer as charming yet insidious, and amusing yet maniacal -- a loose cannon that no one dares to mess with. Part of the film's greatest suspense is not knowing what Costello is going to do from one minute to the next.

Needless to say, Costello is far from being your stereotypical crime boss. Bubbling with menace, you'd swear that you're watching his Joker again from Tim Burton's "Batman" -- yet the character is hardly cartoonish. In fact, he's downright frightening. Even when he talking about weeding out the "rat" in his gang's midst, he feigns the actions of a rat. It's the sort of sight that makes you laugh and send a shiver up your spine at the same time.

While Nicholson is in a league of his own, DiCaprio and Damon take huge steps as the ambiguous infiltrators. Playing a tortured soul throughout, it's far and away DiCaprio's best performance for Scorsese. As for Damon, who often brings a "good guy" charm to his roles, it's refreshing to see him take on one that challenges his usual screen persona.

Perhaps stealing the thunder from DiCaprio and Damon, though, is Mark Wahlberg, who gives a riveting performance as one of the cops protecting Costigan's undercover identity. Overflowing with macho swagger, Wahlberg delivers some of the movie's best comic relief, but at the same time, he maintains his credibility as a man who genuinely cares about protecting the public. He's a spiteful jerk, yet you can't help but admire his integrity.

Solid in supporting roles are a stately Martin Sheen and darkly comical Alec Baldwin, who deliver as expected as part of the cop's undercover unit, as well as Ray Winstone ("Sexy Beast"), who gives a winning performance as Costello's grizzled right hand man. Also pivotal to the film is Vera Farmiga ("The Manchurian Candidate"), who's a knockout as a police psychiatrist in the middle of a love triangle -- though an improbable love triangle -- involving Costigan and Sullivan.

For all "The Departed" has going for it, it's not perfect. The story meanders from time to time and from a filmmaking standpoint, it sometimes becomes too stylish for its own good. But when you have arguably one of the best casts in years, there's far too much glue to prevent "The Departed" from falling apart.

When all is said and done, "The Departed" may not top Scorcese's mob epic "GoodFellas," but there's no question that it runs a strong second. Whether you think it's better or not, it won't be hard to realize that "The Departed" far exceeds most of this year's offerings.