Warner Bros. has released a new banner for Ruben Fleischer's upcoming 1940s-crime flick Gangster Squad.  The movie is set in Los Angeles, and stars Sean Penn as real-life gangster Mickey Cohen, who became the target of special task force known as the “Gangster Squad”.  The impressive cast also includes Josh Brolin, Ryan Gosling, Emma Stone, Nick Nolte, Michael Peña, Anthony Mackie, and Giovanni Ribisi.  Since the film is about six weeks away, I expect we'll see a new trailer in the not-too-distant future.  The first trailer was a bit of a let-down, but I love this cast and setting, so hopefully our next look at the film will be a better one.Hit the jump to check out the banner.  Gangster Squad opens September 7th.Via Yahoo! Movies.gangster-squad-poster-bannerHere's the official synopsis for Gangster Squad:

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. "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.