Benedict Cumberbatch will star alongside Johnny Depp in an upcoming film biopic of notorious US gangster and murderer, Whitey Bulger. Guy Pearce had initially landed the role of Billy Bulger, the brother of crime lord Whitey. Unfortunately, as the producers told Variety, "We were not able to make it work with Guy." Hence, Cumberbatch is replacing Pearce who was forced to drop out of the movie due to scheduling issues. 

Benedict Cumberbatch
Benedict Cumberbatch will star in Black Mass as Billy Bulger.

Depp will be playing Whitey and the pair are supported by a host of other A-List stars including Sienna Miller (Layer Cake), Jesse Plemons (Breaking Bad) and Rory Cochrane (Argo).

The movie, entitled Black Mass, is based on the book Black Mass: The True Story of an Unholy Alliance Between the FBI and the Irish Mob, written by Boston Globe reporters Dick Lehr and Gerard O'Neill. The movie will follow the lives of the two brothers especially the links between Whitey's gang and a former FBI agent, John Connelly (Joel Edgerton). Connelly was sentenced to 40 years in prison for aiding and abetting Whitey, despite maintaining his innocence. 

Johnny Depp
Johnny Depp will star as Whitey Bulger.

Read More: Johnny Depp To Star As Notorious Boston Gangster In Black Mass.

Whitey was on the FBI's Top 10 Most Wanted List for a series of offences involving organised crime. He was on the run for a number of year, finally apprehended in 2011 after 16 years on the run. He was involved in crime from a young age and was even imprisoned in Alcatraz during the 1950s. He was sentenced last year to two life sentences on numerous charges including 11 murders.

His brother, Billy, meanwhile went on to live a prosperous and legal life, even becoming the Senator of Massachusetts. Unfortunately for Billy, he was forced to resign after refusing to give evidence in 2003 about communications he may have had with his elder fugitive brother. 

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Both brothers, James 'Whitey' and Billy Bulger, are still alive. 84-year-old Whitey currently resides in Arizona in a state prison whilst his younger brother, 80-year-old Billy continues to live in Massachusetts. 

Black Mass began filming on Wednesday in Boston and is due to be released in October 2015.

Guy Pearce
Guy Pearce was forced to drop out of the movie due to scheduling problems.