In the 1970s James 'Whitey' Bulger was one of the most feared mobsters in South Boston. In 'Black Mass,' Depp headlines as the notorious criminal — but did he get it right? Bulger's confidants had their say.

From The Godfather movies and Goodfellas to Boardwalk Empire and The Sopranos, there has been no shortage of gangster movies infiltrating pop culture. But in 1970s South Boston, there was perhaps no criminal more notorious or feared than one James Bulger – a sociopath with piercing blue eyes and hair so blond people nicknamed him “Whitey.” Not to his face, of course.

Back in his day, the Winter Hill Gang leader became something of a legend thanks to his distinct “partnership” with the FBI, and more specifically with agent John Connolly — a childhood friend who signed Bulger up as a confidential informant, freeing him up to continue his bad behavior while climbing the underworld ranks. It’s a story that has been told through various news reports and novels over the years, but not so often on the big screen. Until now.

Black Mass features Johnny Depp taking on the role of Bulger – complete with hair and makeup that translates better onscreen than it does on the poster – and Joel Edgerton as Connolly. A plethora of familiar faces, including Jesse Plemons, Kevin Bacon, Corey Stoll, Peter Sarsgaard, Benedict Cumberbatch and Dakota Johnson round out the rest of the cast.

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Joel Edgerton as agent John Connolly and Johnny Depp as Whitey Bulger in 'Black Mass.' (Photo: Courtesy of TIFF)

Despite the fact that it’s been dubbed the project to break Depp out of his “career slump,” none of the story is told through Bulger’s eyes. Instead, director Scott Cooper hones in on Connolly’s story, and then rounds out the rest of the narrative with confessional interviews as told by Bulger’s former crew. It all culminates in a chilling look at a renowned serial killer, but that doesn’t exactly make it a factual tale.

“We’re telling a true story, but what is the truth?” asked Edgerton ahead of Black Mass’s debut at the Toronto International Film Festival. “How much of the truth do we know? At some point you have to plant your flag in the ground and say, ‘This is our truth.’ This is Scott’s vision based on the book.”

“I wasn’t making a documentary and I don’t think audiences come to narrative features for the facts,” added Cooper. “They come for psychological truth, deep emotion and humanity.”

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Benedict Cumberbatch as William Bulger and Depp as Whitey Bulger in 'Black Mass.' (Photo: Courtesy of TIFF)

Depp, who already has a role of this sort on his resume thanks to the 1997 flick Donnie Brasco, has a problem referring to Bulger as a “character” given his basis in real life, but also admitted that when he reached out to the criminal to meet him before playing this version of him, Bulger declined.

“About a week after I made the request I got a message saying that Jimmy respectfully declines as he is not a great fan, as you can imagine, of the book – nor any of the books,” Depp revealed.

Instead, Depp interviewed Bulger’s lawyer, J.W. Carney, who agreed to give Depp some facts, but not to break any attorney-client privileges. “He would never put his client into any sort of weird situation, but he was very helpful,” Depp added. “He helped me get to the heart of Bulger. I hate to say the character, but the heart of the man. There’s very little surveillance footage, there’s very little audio, but people of South Boston were incredibly helpful.”

To hear Cooper and Depp's colleagues talk about the actor’s transformation into this chilling man, he managed to capture the essence of Bulger just fine with the intel he had.

“It’s magic, what he does. There’s the exterior, of course, but it was something coming from the inside that was the most affecting thing,” said Julianne Nicholson, who plays Connolly’s wife Marianne in the film.

“We’re all around very calloused crew members who go from movie-to-movie-to movie,” added Cooper. “There were certain scenes in which you could see people watching the monitors; it was taking their breath away. As a film director that’s a rare place to be.”

Depp, who was frank about wanting to thank the director for “reviving his career” with this role took it all in modestly, looking down and blushing before patting Cooper on the arm. Given that the real Bulger is locked away serving two consecutive life sentences, it’s doubtful he will ever get to see the final product and relay any feedback to Depp. As for the next best thing, Bulger’s lawyer Carney?

“He came by the set and was watching us film for a couple of hours, which was unnerving,” Cooper recalled. "I could see him sitting there staring at the monitor shaking his head. I introduced myself and said, ‘Were we just not getting it right?’ He said, ‘No. Scott… that man, it’s as though it’s a ghost. The way he moves, the way he talks. His accent. The way he holds himself…’ At that point I knew we were on the right path."