Sean Penn does the best gangster impression since James Cagney in 1931’s “The Public Enemy” in a new theatrical trailer for the film “Gangster Squad.” He ruthlessly takes over Los Angeles in the 1950s.

Although the film is ostensibly about a rogue band of LA police detectives, led by Josh Brolin and Ryan Gosling, Penn looks like he steals the movie, judging from the clip.

Penn, 52, plays tough New York mobster Mickey Cohen who moves to Los Angeles in the 1940s intent on taking over the criminal world. His gang is so tough, Nick Nolte, who plays LA Police Chief Bill Parker, creates an off the books squad to wipe out Mickey’s gang. There are no rules; it’s kill or be killed in an all out war.

The movie is based loosely on real life gangster Meyer Harris “Mickey” Cohen, a member of the “Jewish” mafia in LA. He lived a violent, crime-filled life, yet died in his sleep in cozy retirement.

Penn utters a lot of pithy one-liners in the trailer that the real Cohen likely never came close to saying. In that sense, he’s a caricature of the mobster like Al Pacino was of drug kingpins as Tony Montana in the 1983 cult classic “Scarface.”

Emma Stone plays floozie Grace Faraday, who falls for Gosling’s character Sergeant Jerry Wooters. She’s drop dead sexy in the trailer but evokes images of Jessica Rabbit in 1988 film “Who Framed Roger Rabbit?”

“The Public Enemy” and to a certain extent “Who Framed Roger Rabbit?” examined the social forces that underpinned organized crime. Whether “Gangster Squad” includes the same moralizing, or is just a bang, bang, shoot ’em up thriller remains to be seen.

Check out the trailer below and click here to follow TheImproper on Twitter for more flim updates.