Benedict Cumberbatch joining Johnny Depp's Biopic 'Black Mass'. From Screen rant

After four years of playing the world’s greatest detective for the BBC – no, not Batman, Sherlock Holmes – Benedict Cumberbatch is set to take part in a more modern tale of crime and corruption. Cumberbatch has reportedly signed on to join the cast of Warner Bros’ Johnny Depp fronted gangster biopic, Black Mass.

Based on the 2001 non-fiction bestseller Black Mass: The True Story Of An Unholy Alliance Between The FBI And The Irish Mob, Black Mass focuses on the life and times of infamous Boston crime boss James “Whitey” Bulger. Bulger spent much of his criminal career working as an informant for the FBI, leading the bureau to ignore Bulger’s rampant criminal activity (including multiple ordered assassinations) in exchange for his help. Bulger was even able to flip several FBI agents to the dark side outright.

In the mid-90s, Whitey’s relationship with the feds soured, leading to the issuing of an indictment. One of Bulger’s FBI confidants tipped him off concerning the impending action, sending the mob kingpin into hiding for 16 years. Whitey Bulger was finally captured in 2011, and is currently serving two consecutive life sentences in federal prison for his crimes.

Depp has long been attached to the project, and is set to bring Bulger’s persona to life on the big screen, in much the same way he did for infamous bank robber John Dillinger in the 2009 Michael Mann film Public Enemies. Crazy Heart director Scott Cooper is helming the project.

According to The Boston Globe, Cumberbatch – recently of geek friendly franchises like Star Trek and The Hobbit - will now portray Whitey’s law-abiding brother Billy Bulger, a former Massachusetts congressman. While political opponents sometimes tried to use Billy’s ne’er-do-well brother against him, he was never implicated in any of Whitey’s criminal behavior. Cumberbatch is replacing Iron Man 3 and Prometheusvillain Guy Pearce in the role. The exact reasoning for the change has not been revealed.

Other prominent cast members include Dakota Johnson (Fifty Shades of Grey), Juno Temple (Maleficent), Joel Edgerton (Zero Dark Thirty), and Jesse Plemons (Breaking Bad). Bane himself, Tom Hardy, was at one time in negotiations to play the role of Bulger’s corrupt FBI handler John Connolly, but that role eventually went to Edgerton.

It’s obviously a matter of personal preference as to whether Cumberbatch or Pearce is a better choice to play Billy Bulger, as both are more than capable actors. Profile wise, Cumberbatch’s inclusion is likely to get the film a bit more press, as Pearce’s career trajectory hasn’t exactly set the world on fire as of late.

Fresh off of voicing Smaug in the first blockbuster sequel to The Hobbit, it would appear that Cumberbatch has nowhere to go but up. Of course, in the grand tradition of Hollywood biopics, neither Cumberbatch or Depp bear even a remote resemblance to the real life Bulger brothers.