Black Mass is based on the true story of Whitey Bulger, a notorious criminal in Boston. He was involved in organized crime, including drug dealing, extortion, and murder. The movie shows his rise to power within the criminal underworld and his complex relationship with the FBI, who at times used him as an informant while he continued his criminal activities.
The true story behind 'Black Mass' revolves around James 'Whitey' Bulger. He led a violent and criminal life. It shows how he managed to evade the law for a long time. His actions had a major impact on the city of Boston. For example, his gang's activities instilled fear in the local community. The story also delves into the corruption within the law enforcement agencies that had dealings with him.