The first trailer for director Ruben Fleischer's (Zombieland) crime drama Gangster Squad has gone online. The film stars Sean Penn as gangster Mickey Cohen, and centers on the Los Angeles task force (headed by Josh Brolin) assembled to bring him to justice.  I'm a sucker for anything 1940s-related, but I think this trailer is pretty damn great.  The cast is incredible, and Fleischer's visual flair from his previous films looks to have matured and evolved for this more dramatic story.  Above all, though, Gangster Squad looks like a lot of fun.  It's easy for period pieces like this to be drowned by solemnity (I'm looking at you, Public Enemies), but Fleischer hasn't forgotten that there's a lot of fun to be had in 1940s L.A.  Additionally, I'm loving the different personalities on display in the ensemble.  Between this, Argo, and the slew of movies slated for this fall/winter, 2012 is shaping up to be something special.

Hit the jump to watch the trailer.  The film also stars Ryan Gosling, Emma Stone, Nick Nolte, Michael Peña, Anthony Mackie, and Giovanni RibisiGangster Squad opens later this year.

Click over to Apple to watch in HD.

Here's the official synopsis:

Los Angeles, 1949. Ruthless, Brooklyn-born mob king Mickey Cohen (Sean Penn) runs the show in this town, reaping the ill-gotten gains from the drugs, the guns, the prostitutes and–if he has his way–every wire bet placed west of Chicago. And he does it all with the protection of not only his own paid goons, but also the police and the politicians who are under his control. It’s enough to intimidate even the bravest, street-hardened cop…except, perhaps, for the small, secret crew of LAPD outsiders led by Sgt. John O’Mara (Josh Brolin) and Jerry Wooters (Ryan Gosling), who come together to try to tear Cohen’s world apart. “The Gangster Squad” is a colorful retelling of events surrounding the LAPD’s efforts to take back their nascent city from one of the most dangerous mafia bosses of all time.

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