ROMEO AND JULIET IN THE MOB WORLD OF THE 1940S: Sergeant Jerry Worters (Ryan Gosling, right) finds himself falling in love with a moll (Emma Stone) from Mickey Cohen’s mob, the mob that Worters has been assigned to break up. What to do, what to do. To find out how it turns out, see the movie.

Mickey Cohen (Sean Penn) was born and raised in Brooklyn where he started out as a prizefighter before moving to Chicago during Prohibition to become an enforcer for Al Capone. In the 40s, he was sent by Meyer Lansky to Los Angeles to establish extortion, gambling, prostitution, and loan shark operations on behalf of the Jewish Mafia.

Mickey gradually began to make inroads, which didn’t sit well with Los Angeles Police Chief Bill Parker (Nick Nolte) who was determined to prevent any crime syndicate from gaining a foothold in his city. But that would prove to be easier said than done since the mobster had already succeeded in bribing and/or intimidating many cops, judges, and powerful politicians.

In light of the frightening degree of corruption, Parker decided that the only way to bring down Mickey was to behave just as ruthlessly as he did. So, Parker asked one of his most fearless officers, Sergeant John O’Mara (Josh Brolin), to form a top secret team whose mission would be to enforce the law by breaking it.

The so-called gangster squad’s mission was simply to enter each of Cohen’s establishments anonymously and break kneecaps and generally trash the place. Of course, if any of O’Mara’s operatives were killed or captured, the police commissioner would have to disavow any knowledge of their actions.

Gangster Squad is a stylized costume drama with far more charm than one would ordinarily expect to find in a ganster movie. Directed by Ruben Fleisher (Zombieland), the film is based on the Paul Lieberman bestseller of the same name.

The production has an A-list cast which includes Sean Penn, Ryan Gosling, Josh Brolin, Emma Stone, Nick Nolte, Anthony Mackie, Giovanni Ribisi, Michael Pena, Robert Patrick and Mireille Enos. Therefore, there are no throwaway roles here, and even lesser characters are developed because the veteran cast members put their experience into their performances.

As a result, the audience cares not only about whether or not Mickey will ever be brought to justice, but about surprisingly engaging subplots such as a lawman (Gosling) going gaga over the gangster moll Grace Faraday (Stone), and about a pregnant wife’s (Enos) fear that her husband Sergeant John O’Mara (Brolin) will not live long enough to see his baby being born. Nevertheless, the front story does feature all the staples of the genre, such as flashy zoot suits, tommy guns, and street-smart dialogue that mixes slang and savoir faire in a manner reminiscent of Damon Runyon.

Excellent (****). Rated R for profanity and graphic violence. Running time: 113 minutes. Distributor: Warner Brothers.