Black Mass is a crime drama film where Benedict Cumberbatch plays Billy Bulger, a prominent politician and brother of notorious gangster Whitey Bulger. The film tells the true story of Whitey Bulger's criminal empire and the FBI's attempts to bring him down. Cumberbatch's performance as Billy Bulger showcases his versatility as an actor, portraying a complex character torn between loyalty to his brother and his political ambitions. Black Mass is a gripping and intense crime thriller.