Black Mass, the brilliant new film about the rise and fall of crime boss James Whitey Bulger, is one of the most impressive crime dramas out of Hollywood since the glory days of the 1970s. Tense, flawlessly acted and filled with unsettling questions that have no easy answers, it’s Oscar bait of the highest caliber. CAHIR O’DOHERTY talks to Gerard O’Neill, the Pulitzer Prize winning author who wrote the definitive life of Bulger on which the film is based.

Johnny Depp has finally found the big film role that could bag him that elusive Oscar. Unfortunately for Irish America it’s the role of notorious South Boston gangster James “Whitey” Bulger in the stunning new film Black Mass, which opens on Friday.

Irish America has produced many remarkable men and women. Bulger wasn’t one of them. In South Boston in his gangland heyday in the seventies and eighties the local Irish community knew that Bulger was a bad guy, but he was their bad guy, and if he wasn’t exactly admired many respected him.

That was before they heard that he’d been strangling young women with his bare hands, of course. The tough as nails neighborhood that had raised him drew the line at that kind of depravity.

Then they learned Bulger had been an FBI informer for most of his bloody reign. The news kept getting worse and worse. The tough guy they thought they knew turned out to have been depraved beyond their worst imaginings and a stool pigeon to boot, the lowest rung on the criminal ladder.

Depp is almost unrecognizable as Bulger in Black Mass. His famously brown eyes have been turned icy blue by contact lenses, and his receding hairline gives him a hawk-like intensity in every scene he’s in. He’s terrifying, in other words, every inch the sociopathic killer that Bulger eventually became.

But Depp doesn’t make his spine tingling character a cardboard cut-out psychopath. He’s also the local boy who helps old ladies with their shopping before shooting someone in the head in the very next scene. The shocking contradictions only serve to make the mystery of who Bulger really is all the more disturbing.

Critics fearing that Hollywood might romanticize Bulger’s bloody reign will be relieved, because Black Mass is not that movie. Film goers hoping for a shoot em’ up with a tidy moral ending will be surprised by the maturity of the script and the questions it asks.

What we have here is a film that becomes a crime classic as you watch it. Not a scene is wasted, and the true story of Bulger’s rise and fall is told.

“I’m happy with the film,” Gerard O’Neill, the Pulitzer Prize winning author of Black Mass, the book on which the film is based, tells the Irish Voice.

“My interest was how Bulger was able to co-opt the FBI into his schemes through the federal agent John Connolly who grew up in the same South Boston Old Harbor housing projects.”

Connolly, who would later face prosecution himself, was “star struck” by Bulger, O’Neill says. “When he was a little kid Bulger was a local hero in Southie and that set the tone for their relationship.”

The Bulger that is presented in the movie is concerned about his mother and his brother, he is concerned about The Troubles in Ireland, he helps old ladies with their daily shopping. There are other sides to his character than just the crime land boss on the make.

“He’s a very complicated guy. He could be charming in his own way,” O’Neill says of Bulger.

“He’s very conscious of his persona and how it affects people. In fact it’s very similar to the way a politician would view relationships. He was quite calculating, it seemed to me.”

As luck or irony would have it, Bulger’s brother was William M. Bulger, the most powerful politician in the state (he himself did not consider his relationship to the most notorious hoodlum in the state as lucky). But blood ties were the currency of South Boston.

So Whitey Bulger’s luck was remarkable. He was protected by both the FBI and his relationship to his kingmaker brother. It was an only-in-Boston development that startled O’Neill.

“I remember suddenly realizing the depth and breadth of the corruption. It wasn’t just this dubious personal relationship with one agent,” says O’Neill

“Bulger had subsumed the Boston office of the FBI. It wasn’t just that John Connolly had been corrupted by Bulger. It was much more systemic.”

The worry then – and now -- is that the FBI has been for too long addicted to informant intelligence, and questions remain about how those relationships get sealed.

“That’s the basis for the corruption, when law enforcement starts to look the other way to protect or even abet their informants. That’s the trap of all that stuff,” says O’Neill.

“The informant relationship is the coin of the realm, but it gets quite poisonous if its not properly overseen. One agent can have an informant and the supervisors may not know – or know enough – about the relationship. Therein lies the danger.”

Critics will garland Depp’s career best performance, but as John Connolly, the agent that Bulger seduces and corrupts, Joel Edgerton also gives a standout supporting actor performance. It’s a portrait of a good man being outmaneuvered and losing the run of himself, and Edgerton is superb in the role.

“Joel captures the dire difficulty of trying to run somebody like Bulger and still stay in charge,” says O’Neill. “It was pretty clear to me pretty quickly that it was Bulger who was really calling the shots.”

Black Mass has captured the conflicting ethical questions that people slip into in that world, and that starts to take everybody down, O’Neill adds.

Other perennial Irish themes keep emerging in the film too. Loyalty to the tribe is preeminent, even when you know some members are doing bad things.

There’s also the special contempt that Irish people have for informants. Bulger shared that contempt himself and only became an informer once he knew for certain it would never become known, and that it would probably only serve to protect his own schemes.

“It’s not surprising that these themes manifested themselves so strongly in South Boston, it was a very Irish place when all this stuff was going on. It was almost ungovernable in some ways.”

The people of South Boston have always felt themselves a place apart from Boston itself, and there have been boundaries and borders there. “It’s not as intense now as it was in the time of Whitey’s heyday, but it was a real thing back then,” says O’Neill.

Back then Bulger had a Robin Hood quality, at least in the beginning. He might have been a bad guy, but he was our bad guy.

“People didn’t understand how bad it was, I think. His strangling women wasn’t known, and when that came out it put him in a whole different category,” says O’Neill.

There was a Rubicon of bad deeds that Bulger crossed. You don’t stay a local hero in South Boston if you’re strangling young women. But that didn’t become commonly known until long after it happened.

And what’s Bulger’s legacy in South Boston now? Is there one?

“That’s changed as South Boston itself has changed. It’s been yuppified. The Southie of his time was a really different place. Once he dominated it through fear and a screwy bad guy charisma, I guess,” says O’Neill.

What is the lesson of his rise and fall? “It’s that crime doesn’t pay I guess. Even Whitey Bulger winds up getting caught.

“I don’t now that there’s any profound lesson in it. He was able to control his neighborhood with an iron hand and he did it through fear and charm. But he lost in the end. He was a bad guy, he was a murderer, and he created an empire through sheer terror. He was a bad seed. His 11 murders are his testimony.”