The Gangster Squad EW Photo Featuring Josh Brolin and Sean Penn

"It's a good leaping-off point. We've taken some creative license but tried to stay true to the original story and characters as much as possible. O'Mara (Josh Brolin), our lead character, has just come back from fighting the Nazis with all these ideals after seeing America at its greatest. And he's come home and there's a gangster running his city. While he was gone, Mickey Cohen (Sean Penn) took over and he turned the streets of L.A. into a battle zone. In our story, O'Mara takes the lead of The Gangster Squad, a vigilante police force that fights the gangsters on their own terms, and the battle between them is for the future of Los Angeles: whether it's going to become corrupt and run by this bunch of gangsters or these guys who fought for these values and want L.A. to be the shining beacon on the west coast that it was always intended to be."

"These places don't exist anymore. We had to take blocks of streets and build period storefronts and recreate clubs that have been closed for years. The past two nights, we had a full tommy-gun battle inside the Chinese Theater with gangsters lighting off 50 rounds a minute. And then tonight and the next night, it's going to bleed out onto Hollywood Boulevard as our Gangster Squad retreats. We're going to have a full battle on one of the most famous streets in L.A. And staging a scene at the Griffith Park Observatory is just iconic because you instantly think of Rebel Without a Cause and all the great movies that have filmed there. On Monday, we were on the steps of City Hall with Nick Nolte. It's like going in a time machine when you go to the set."

"Ultimately it's the story between these two guys. It's Josh and Sean who face off at the end after a big gun battle between The Gangster Squad and Cohen and his men. O'Mara catches up to Cohen and Sean mockingly says, 'Okay, copper, take me in.' It ends in a fistfight between Cohen and O'Mara, and it was a pretty epic sequence to film between Josh and Sean."