“The Departed” Starring: Leonardo DiCaprio, Matt Damon, Jack Nicholson, Mark Wahlberg, Martin… “The Departed” Starring: Leonardo DiCaprio, Matt Damon, Jack Nicholson, Mark Wahlberg, Martin Sheen, Alec Baldwin. Directed by Martin Scorsese

out of

Rats in the statehouse? Shoot ’em.

At least, that’s what Martin Scorsese’s “The Departed” might shout at you the first time you see it.

The story opens in Boston, with Frank Costello (Jack Nicholson) delivering a monologue on the good life – in his case, the criminal life. Soon afterwards, we discover that Costello, just like the rest of the characters in “The Departed,” is incredibly brutal.

Costello relies on two men to do his dirty work: Colin Sullivan (Matt Damon) and Billy Costigan (Leonardo DiCaprio). Costigan, recruited as an undercover agent, infiltrates the local crime ring and becomes a thug for Costello.

Sullivan, who grew up with Costello as a benefactor, is already loyal to the same crime ring when he is recruited by a special investigations unit to, you guessed it, investigate Costello. “The Departed” revolves around these two infiltrators trying to rat one another out.

Now just throw in a woman who has relations with Costigan while she lives with Sullivan (Sullivan is just sooo funny and Costigan is such a badass, so why not have both?) and you have the recipe for a blockbuster.

All cynicism aside, “The Departed” marks the most entertaining film of the year thus far. DiCaprio proves that he isn’t a boy anymore: He performed strongly in “The Aviator,” but here he shows a darker side that doesn’t dwell on his inherently harmless and innocent character.

In fact, he does quite a bit of harm in “The Departed.” After serving jail time to make his record believable, he enters a bar in which he smashes a glass of cranberry juice into a guy’s face. Why? The guy told him that only girls drank cranberry juice. For the full two-and-a-half hour runtime, DiCaprio pulls off calculated mischief.

Nicholson’s Costello is creepy and criminally insane – probably from all the coke he does. Matt Damon brings in a Boston attitude reminiscent of “Good Will Hunting,” capturing Sullivan with a handful of weird idiosyncrasies.

But the real surprises are the breadth and sense of humor added by Dignam (Mark Wahlberg), Oliver Queenan (Martin Sheen) and Ellerby (Alec Baldwin). The three have low screen time, but they transform what they’re given into unforgettable roles.

Dignam, an antagonistic, 100-percent-Boston cop with a strong sense of justice, isn’t afraid to tell off people like Ellerby, an FBI agent. Ellerby, in turn, is unusually light-hearted for a federal agent and far too trusting of Sullivan.

Both are filled with glib remarks, but Wahlberg’s biting attitude gives him an edge. Best supporting actor? That sounds about right.

Although “The Departed” doesn’t reflect Scorsese’s best filmmaking, it certainly has interesting moments. Early on, there’s some nice crosscutting going on between Sullivan and Costigan as they begin their new jobs: Sullivan as a crooked detective and Costigan as a noble criminal. The flow, while complicated, is highly intuitive – you’re more likely to be confused by plot twists than the structure of scenes.

The last 20 minutes drag a bit, until they run into the last five. Then “The Departed” pivots, knocking you upside down. It’s brutally violent, the players have no remorse and it’s not a Hollywood ending.

The audience gasped, then laughed nervously – they didn’t know how else to react. Things fall into place in the last minutes, and you might find yourself thinking that this is how a modern tragedy should be done.