Martin Scorsese sure knows how to have a kick-ass time.

After a few years of unsuccessfully trying to win Oscars, Scorsese returned to his roots: violent men inhabiting mean streets. It seems to work for him. With "The Departed," he has made a more confident, self-assured film than his previous epic, award-begging vehicles "Gangs of New York" or "The Aviator." Ironically, this film is now a prize contender.

A remake of the Hong Kong film "Infernal Affairs," "The Departed" faces the same challenges that face all adaptations: finding a balance between keeping a similar plot line and an original take on the story.

Much of this balance is accomplished through the film's setting. This time, South Boston's Irish working-class communities are the backdrop. Colin Sullivan (Matt Damon) and Billy Costigan (Leonardo DiCaprio) are graduates of the police academy. Sullivan is invited into the upper echelon of the force while secretly informing Frank Costello's (Jack Nicholson) Irish mafia. Costigan does the reverse, informing the police while working within Costello's mob.

Nobody likes a rat in their circle. Police Chief Queenan (Martin Sheen) and Costello (Nicholson) each realize they have one, but flounder trying to find who it is.

Scorsese slowly lowers us into this brilliant set-up, allowing it to increasingly envelop the viewer as he raises the stakes. Loyalties are constantly shifting, and there is no easy moralizing of any character's plight or superiority.

The idea of the informant is nothing new. During a house call, a clip of John Ford's exemplary "The Informer" plays in the background. In the Irish cultural tradition of both films, informing is the most despicable thing a man could do, punishable by an execution carried out by former friends. The sides of the battle have to remain clear if either side is to succeed.

In this world, there is no guarantee of safety, regardless of which side you are on. At the beginning of the film, the Rolling Stones' hit "Gimme Shelter" blasting, Costello tells a young Sullivan that it doesn't matter whether you're in the police or the mafia when there's a gun in your face. In that moment, we all become the departed.

Sides may not matter, but morals and honor do. The double lives that Sullivan and Costigan live rips them apart and affects all aspects of their lives. DiCaprio's performance is more exterior and more successful, as viewers watch him quickly transformed from clean-cut cop to dirty, drug-dealing gangster. Damon may have the girlfriend (up-and-comer Vera Farmiga) and the cash, but he is no more at peace than DiCaprio. The world of the informer is never enjoyable; he always looks over his shoulder for someone out to get him.

Scorsese was one of the directors propagating the realism movement to the multiplexes during the Hollywood renaissance of the early- to mid-1970s. He works within this genre better than most, and films of his, such as "Taxi Driver," stand the test of time as indelible character sketches set against fascinating modern situations. In a particularly heated moment, Nicholson screams at one of his thugs, "This ain't reality TV!" But, in style and essence, it is?"The Departed" subscribes to the 21st century's incarnation of the cult of realism.

Realism does not assure success, however. As entertaining as these double-crossings are, "The Departed" does not linger in the mind for very long. Violence begets violence, but one has a sense leaving the theater that "The Departed" leaves the whole world blind with nothing to show for it.

In other film news, this weekend, Eveningstar Cinema opens Philip Noyce's "Catch a Fire," starring Derek Luke and Tim Robbins. The film is a biopic of Patrick Chamusso, a freedom fighter against the Boer government in South Africa in the 1980s. Highly relevant to the current political climate, it should not be missed. It will show at 1:30 p.m., 4 p.m., 6:30 p.m. and 8:45 p.m.

Showing one time only is "Bullshit," a documentary on Vandara Shiva, a nuclear physicist and environmental activist, as she battles proponents of globalization and a host of other related problems. The screening also features speakers: one filmmaker preparing a documentary on Shiva's farm and two people actively involved in food issues in contemporary society. "Bullshit" will screen Saturday at 10 a.m. Check out

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