Black Mass is a crime drama film based on the true story of notorious Boston gangster Whitey Bulger. Benedict Cumberbatch plays Billy Bulger, Whitey's younger brother and a prominent politician. The film delves into the complex relationship between the two brothers and the web of corruption and violence that surrounds them. With its gritty atmosphere, intense performances, and gripping narrative, Black Mass offers a compelling portrayal of organized crime and its impact on society.