Playing out of competition, today’s Venice Film Festival gala entry Black Mass screened for press at an early call this morning with strong applause at the end — twice. Audiences should be cautioned to stick around as there’s a key footnote at the end of the Scott Cooper-helmed crime drama. Johnny Depp has been getting some career best notices for his chameleon-like turn as James “Whitey” Bulger, the notorious leader of Boston’s Winter Hill mob who is now serving two life sentences for murder and other crimes. Bulger was a ruthless mob kingpin in 1970s Boston who spent a decade on the FBI’s Ten Most Wanted list. He went on the lam in 1994 and was finally captured in 2011 in Santa Monica. He turned 86 yesterday.

Also stirring up great praise is Joel Edgerton who plays FBI agent John Connolly, a childhood pal of Bulger’s and his brother Billy (Benedict Cumberbatch, also very strong) who grew up to be a powerful state senator. The story kicks off when Connolly returns to South Boston with the goal of getting rid of the Italian mafia in the North part of the city. He strikes an “alliance” with Bulger which sees the criminal provide information to the Feds in tacit exchange for basically being untouchable. The Guardian wrote this morning that Black Mass is “acted and directed with tremendous confidence and verve” and called it a “major comeback” for Depp whose recent pics Transcendence and Mortdecai fizzled.

However, Sienna Miller, who was playing Bulger’s girlfriend in his fugitive years, has been excised from the film. Cooper told the Boston Globe she had been “fantastic.” But a decision was made to focus on the mobster’s earlier life. “It came down to narrative choices,” he said.

The title of the film comes from the 2001 bestseller Black Mass: The True Story Of An Unholy Alliance Between The FBI And The Irish Mob which was written by Dick Lehr and Gerry O’Neill (they have a cameo in one scene in the film, but are not playing themselves).

There are some shadings of The Godfather and Goodfellas including one chilling scene reminiscent of the “Funny how?” moment from the latter. And The Departed gets a nod here too — both pics are set in Boston (in fact, Venice is starting to feel like Beantown on the Adriatic after yesterday’s Spotlight and Black Mass today).

This is a film that went through a series of growing pains. It was originally set up with Universal distributing through producer Cross Creek’s deal with the studio. At the time, Barry Levinson was attached to direct Depp who later exited over a salary dispute in May 2013. Fast forward to January 2014 and Crazy Heart‘s Cooper was set to direct with Depp back in the mix. Then, in late February 2014, Warner Bros came aboard to co-finance and take worldwide distribution as previous backer Exclusive Media imploded in Berlin that same month.

Warner Bros is starting the international rollout on Black Mass on September 17 after hitting both Telluride and Toronto.