Penn portrays Mickey Cohen, a relocated East Coast boxing champion who is taking over California in 1949. At the beginning of the film, we see just how unflinchingly violent he is as all gangsters obviously are.
In the middle of the desert Cohen has Random Guy #1's arms and legs tied to separate vehicles. His punishment from an unknown betrayal is to be ripped in half as the cars pull him in opposite directions. This scene and the ones that follow are successful in proving that no one should mess with Cohen. (Warning to those who are squeamish towards violence - this movie definitely is.)
Josh Brolin plays John O'Hara the face of honor and duty, a cop returned from the war not willing to let Cohen take over this new promising land of Cali. Again at the beginning we see Brolin in action much like Penn.
Trailing Cohen's sick thugs, he finds one of them 'charming' a young lady back to his warehouse apartments, where a gang of men are planning to rape her. O'Hara without a warrant breaks into the place just in time beating up every guy who stands in his way and saving the young woman.
When the chief of police catches wind that O'Hara single-handedly wiped out one of Cohen's prostitution houses, he's assigned to enlist other happy gun and fist slingers to take down Cohen anonymously. The characters who make up this merry band of cop misfits are a great group of underrated actors - Anthony Mackie, Giovanni Ribisi, Michael Peña, Robert Patrick. The group gets along splendidly, and the script doesn't force tension between them or a perfect camaraderie.
The main performances by Brolin and Penn aren't exactly genius. Brolin has a natural charisma and kick-arse attitude that you can easily believe him - especially since he doesn't attempt to caricaturize a 1940s persona.
Penn on the other hand is ridiculously too into his character. The Chicago accent sounds phony in some takes, genuine in others. It doesn't help that much of his dialogue, in contrary to other actors, is filled with 1940s innuendos that would break a smile out on my face. Oh, so funny.
Much of the credit of why this film was entertaining to watch goes to the supporting actors. Ryan Gosling as Jerry - a deputy to Brolin - puts in a modest performance. At first he doesn't want to join Brolin's gangster squad but after an acquaintance of his is shot down in the streets, Jerry is all for revenge.
Actress Emma Stone is meant to be his other half to wake him up from his emotional coma. But I have to say she is really quite boring and uninteresting. As a femme fatale who is tied to Cohen's side, she could have easily made the role more layered but remains more of a tie-in to Gosling because of their Crazy Stupid Love chemistry.
A love interest who proved much more interesting and characteristically perfect for her partner was Mireille Enos as Connie. She plays John's wife who is pregnant. As a female role of the era constricted to the household, she shows brash, emotionality, and independence. In the few scenes Enos shares with Brolin, there is a perfect blend of them showing a genuine love and challenging each other.
Cohen versus O'Hara and his squad comes to a head at the climax of the film set around Christmas. One of the enjoyable parts of the film is the well-choreographed gun fights because you can never guess who is going to come out alive. This one, much like the ones who before, are stylized to a point that heightens the films' thrills and suspense. And when the feuds come to an end, it's a pretty satisfying finale.
Personally when trailers of Gangster Squad were aired in 2012, I thought this would be a motion picture just to laugh and make fun of all the way through because of the ridiculous constant gun fire in public areas and Penn's lack of believability. However about a half hour into the film - despite its flaws - I caught myself immersed. It's not a modern masterpiece on 1940s glam and gun fire but it makes a respectable attempt.
In A Giphy: