Ruben Fleischer’s (“Zombieland”) newest film, “Gangster Squad,” opens in 1940s Los Angeles with the “Hollywoodland” sign looming high on the Hollywood hills.

We quickly realize, however, that this is not the glamorous old Hollywood we think of today.

Organized crime led by mafia kingpin Mickey Cohen (Sean Penn), has taken over. In fact, the opening scene of the movie shows just how horrible things can be when you cross Cohen’s mob; picture the baseball bat scene from “The Untouchables,” except worse.

Through drug deals, prostitution and gambling, Cohen buys himself power and pays many members of the corrupt government and LAPD to turn a blind eye to his crimes. That is, until white knight police Sgt. John O’Mara (Josh Brolin) is tapped to create a clandestine squad of five like-minded police officers who make it their goal to take Cohen down and clean up the streets of LA.

The main conflict in the film is best described by police officer Jerry Wooters (Ryan Gosling), who is at first reluctant to join the squad. “The whole town is underwater and you are reaching for a bucket when you should be reaching for a bathing suit,” Wooters quotes.

Throughout the film, members of the Gangster Squad struggle with what means more to them, money now (in the form of mob payoffs) or security for the future. Should they “put on their bathing suits” like many of their police brethren and let the city fall further into darkness, or should they stick to their guns (literally) and stop the violence from spreading?

As the characters dive deeper and deeper into the criminal world, we find they have made their decision; they would rather have a safer city for their kids to grow up in than any mob money. After all, at least three of the members of the Gangster Squad were World War II veterans who believed their fight for a safer America was over. It turns out there was still a lot of fighting left.

If you have seen the trailer, you have seen Penn play Mickey Cohen as a caricature of the stereotypical Hollywood gangster. This, however, is what actually made him entertaining. It was almost as if he was “cartoonish” and over the top on purpose.

Cohen’s idiosyncrasies are what gave the film a lot of its humor. From freaking out over the appearance of his tie (when he should have been worried about getting out of LA alive) to marveling over how good peacocks taste, Penn’s Mickey Cohen was just as amusing as he was terrifying.

Josh Brolin was also good as the gruff leader of the Gangster Squad, willing to go to the ends of the earth to take down Cohen. However he was regularly upstaged by Ryan Gosling.

Gosling was in his element, playing a charming (typical), tender-hearted police officer who finally joins the squad after Cohen’s mob kills someone he cares about. Besides Robert Patrick, who got laughs in basically every scene, the rest of the Gangster Squad was pretty expendable.

Hands down, the best part of the movie was its noir style, particularly in the set design and costumes. It was impressive how much attention was paid to making the audience feel they were in Los Angeles in 1949.

Another great aspect of the film was the action scenes. Especially entertaining was the car chase involving the Gangster Squad and dynamite. Of course, like in many films, at times the shootouts were cliché.

For instance, to serve Cohen a warrant for his arrest, the Gangster Squad must infiltrate a hotel described as Cohen’s fortress. It is said over and over how dangerous it will be and that this is a suicide mission.

Of course, in true Hollywood-fashion it isn’t really that dangerous since the members of Cohen’s mob are terrible shots, while it’s hard for the Gangster Squad to miss.

My main complaint with the film was in the underdeveloped subplot involving the relationship between Grace (Emma Stone) and Jerry (Gosling). Grace is Cohen’s girlfriend, but she actually wants to be with Jerry.

As shown in “Crazy, Stupid, Love,” Gosling and Stone have incredible chemistry. While they were still great together in this film, the actual “love story” between the two just felt like filler between the different action scenes; there was never much tension over whether or not the two would get caught.

It was frustrating that so much storyline potential was left on the table.

While Gangster Squad felt clichéd and “cartoonish” at times, due to the all-star cast, noir tone and great action sequences, the film starts 2013 with a literal bang. While this was no “L.A. Confidential” or “The Untouchables,” it was still a good popcorn flick.

Rating: B-

LAUREN BRADSHAW grew up in Courtland, graduated from Southampton Academy and doubled-majored in foreign affairs and history at the University of Virginia. She lives in the Washington, D.C., and can be reached at lnb5e@virginia.edu.