“This was our very first day of shooting. Josh Brolin plays John O-Mara, a hard-nosed cop headed into the hornet’s nest—mob boss Mickey Cohen’s HQ. He’s trapped in an elevator with two thugs, but he fights his way out.” Click here to see the slideshow.

There may be no more classically American film than a gangster flick set in Los Angeles on the cusp of the fifties—that pre-tabloid golden age when movie stars were magnificent creatures captivating the public imagination. “It was a glamorous time,” says director Ruben Fleischer, whose Gangster Squad is based on a seven-part series of articles by Los Angeles Times reporter Paul Lieberman. “L.A. was the place to be.” Evidently, Mickey Cohen—a pugilistic Brooklyn mobster, played by Sean Penn—arrived at the same conclusion. Cohen headed west to claim his lot and, with the notoriously corrupt LAPD in his pocket, soon ran all the vice operations in Tinseltown—except for one clandestine crew of renegade cops, led by Sgt. John O’Mara (Josh Brolin) and Jerry Wooters (Ryan Gosling). Known as the Gangster Squad, they had one sole purpose—to take down Cohen, by means legal or otherwise. In the film, Fleischer throws in an illicit romance: The ­roguish Wooters, who according to Lieberman was the most reckless of the Gangsters, courts potentially lethal trouble by chasing Cohen’s flame, Grace Faraday (Emma Stone).

“It’s been a while since people really fell in love with an American gangster movie,” says Fleischer, 37. He may have a point: In recent years, the genre has found its most potent expression overseas, in the likes of Italy’s Gomorrah and France’s Mesrine and Carlos. So when Warner Bros.—a studio built upon the pinstriped shoulders of Jimmy Cagney and Edward G. Robinson—sought to revive one of its most storied cinematic traditions, it called upon Fleischer, who’d previously helmed the surprisingly successful horror comedy Zombieland, for some new energy. “It’s a modern take on the tradition,” Fleischer says, “and hopefully a return to form.”