The movie is based on a book by Los Angeles Times reporter Paul Lieberman, but its tone is like something adapted from a graphic novel - more interesting in striking a lurid, hard-boiled pose than recovering lost L.A. history.
"Gangster Squad" opens by establishing Cohen as a first-class psycho - he punishes a rival mobster by chaining him between two cars, ordering him to be pulled apart, then fed to coyotes.
The animals aren't the only ones chewing the scenery - Penn is borderline berserk here, catching the go-big drift of director Ruben Fleischer ("Zombieland").
Opposite Cohen is square-jawed war veteran O'Mara (Brolin), who recruits a secret team of tough guys ck, Anthony Mackie, Giovanni Ribisi, Michael Pena.
A great cast, though they make the squad probably more racially diverse than it would have been in the late 1940s. The actual anti-gangster unit was assembled by Chief William Parker (played here by Nick Nolte), who did eventually integrate L.A.'s police force, but only after decades of policing that created tension between the police force and minorities that exists to this day.
On the other hand, it's always good to see Pena and Mackie. Ditto Emma Stone, who turns up as Cohen's girlfriend.
She looks smashing. Everyone, in fact, has great clothes. I expect to see Gosling's plaid shooting jacket in the LL Bean catalog forthwith. Accessories include a fedora and Thompson submachine gun. Another accessory - the entire plot of "The Untouchables," shamelessly mined here, as is the production design of "L.A. Confidential." Two great movies. Which may explain why "Gangster Squad," though never very original, is never really dull.