“Like a lot of other stuff in my life, I sort of fell backwards into it,” screenwriter Will Beall says of his unexpected perch atop Hollywood's A-list. Unexpected, because just five years ago Beall was busy working for Tinseltown's second most famous employer, the L.A. Police Department, where he was a homicide detective in South Central's notoriously rough 77th Division. Then he published his first novel, the gritty rookie-cop saga L.A. Rex, which earned Beall plaudits from Joseph Wambaugh, fellow LAPD vet–turned-author, plus a gig adapting the screenplay for über-producer Scott Rudin.

When that script landed in seventh place on 2009's “Black List” — the annual insider survey of the industry's best unproduced screenplays — Beall officially traded in his holster for the latest version of Final Draft.

Today, name a hotly anticipated Hollywood tentpole movie and chances are the 40-year-old Beall is writing it or has been asked to, including two long-gestating projects with large, hard-to-please fanboy constituencies: Logan's Run and the DC Comics all-star jam Justice League. Which, as screenwriting beats go, can definitely be a dangerous part of town.

First up, though, is Gangster Squad, an all-star crime drama opening next week, based on the real 1940s turf war between gangster Mickey Cohen (Sean Penn) and an elite team of L.A.'s finest, led by square-jawed enforcer John O'Mara (Josh Brolin) and morally compromised playboy Jerry Wooters (Ryan Gosling).

Directed with surprising panache by Ruben Fleischer (Zombieland, 30 Minutes or Less) and lustrously shot by cinematographer Dion Beebe, the movie offers a jazzy riff on a familiar subject (see: Bugsy, L.A. Confidential), never taking itself too seriously for its own good.

The performances are plums all around — especially Gosling's — but the true star here is Beall's wry dialogue, as rapid-fire as Tommy gun bursts.

“When the producers asked me who I had in mind for these parts, I was like, 'Uh, John Wayne and Errol Flynn and Barbara Stanwyck,' ” says Beall, who can quote Howard Hawks movies chapter and verse and even based one Gangster Squad character on the ocular-scarred hired gun played by Christopher George in El Dorado.

But when I read one of Beall's zingers back to him — “There's two things you can't take back on this job, pal: bullets out of your gun and words out of your mouth” — he tells me he can't actually take credit for it. “A sergeant of mine, a guy named Frank Mika, used to say that for real.”

Police work is another of those things Beall just sort of fell into. As an English major at San Diego State University eyeing a journalism career, he found himself getting a little too close to a murder investigation he was covering for the campus newspaper. The victim was a fellow student; Beall eventually testified as a witness for the prosecution.

When the dust settled, the district attorney on the case suggested that he should think about becoming a cop.

Joining LAPD in the midst of one of the department's greatest public-image crises — the aftermath of the L.A. riots — Beall asked to be assigned to the 77th, and he soon began keeping a journal that would become the basis for L.A. Rex.

“The guys that I worked for and learned from, some of them had been around since the Watts Riots,” Beall recalls. “We're talking about guys who were firmly rooted to the ground while the storm was raging around them. The cultural and sociopolitical stuff that was happening was so irrelevant to their day-to-day job that it didn't change the way they went about it.

“The feds got involved in riding herd on the department, but these were guys who were treating gangsters and dope dealers with respect and humanity before anybody said, 'This is what you have to do.' They were honorable guys, and honor's about what you do when nobody's looking.”

Honor of that sort might be harder to come by in the screen trade, but Beall has high praise for several collaborators thus far, including Rudin (whom he describes as the equivalent of a graduate screenwriting seminar) and Gangster's Fleischer.

“I think there are a lot of guys who would have said: 'I like the script. Thanks for loosening the jar for me. See you at the premiere,' ” he says. “Which would have been fine, by the way, but [with Fleischer] I got to be involved in a way that I don't think a lot of writers ever do, which was fantastic.

“Maybe he wasn't the most obvious guy for the job, but look at someone like Robert Zemeckis. Before Back to the Future, he made these screwball comedies like I Wanna Hold Your Hand and Used Cars. If you go back and look at them, they're great, and you can see that this guy is going to become a phenomenal filmmaker. It's great to be present at this transition point in [Fleischer's] career, because I really think he's going to be one of those guys that in 20 years people will still be talking about.”

When Gangster Squad was postponed from its original fall 2012 release date in the wake of last summer's Aurora, Colo., movie-theater shooting, Beall and Fleischer quickly mobilized to devise a new sequence to replace a violent mob-ambush scene set inside Grauman's Chinese Theatre (and glimpsed briefly in the first Gangster Squad trailers). “The decision to get rid of that scene was not one that we entered into lightly, but I think everybody felt like it was the right thing to do,” Beall says. “And I think it's actually a better movie with the new scene” — a scene, appropriately, set in Chinatown.

So what's adrenaline-pumping: making arrests or making movies? “I joke sometimes that I think something terrible happened to me when I was a cop and this is all some kind of Jacob's Ladder coma dream or something,” he says with a laugh. “But it's a different kind of excitement. I feel like these are the two most exciting industries in Los Angeles, and I'm lucky enough to have spent some time in both. It's hard for me to answer that question because I was a cop for a little over 10 years, and the writing is still fairly new, but I'm having a lot of fun.”

LA Weekly