Black mass in the true story of the tie up between a FBI agent and a dreaded gangster---both of who grew up in the streets of Boston city of USA since childhood and formed a bond since those days . James 'Whitey' Bulgur ( played by Johnny Depp ) is a deadly gangster who controls crime in south Boston . His brother is a local politician . One day Bulgur is approached through his brother by FBI agent ( played by Joel Edgerton ) John Connolly to help him clean up the mafia of north Boston by informing about the mafia's activities . In return he promises that the FBI will not go after Bulgur . Both intend to use each other---Connolly hopes that the information provided by Bulgur will help him in getting the north Boston mafia and will help in advancement of his career , while Bulgur hopes to expand his criminal activities with the FBI protecting him from being brought to book . Connolly of course is playing with fire....but amazingly he seems to have some romantic notions of the small time favours Bulgur had done to him in his childhood---to the point where his boss sarcastically taunts him about his 'fagggot relationship with Bulgur'... Connolly crosses all limits by even socializing with Bulgur along with his family , to the point where his wife finally refuses to attend the parties . But she has to face Bulgur's wrath , who physically threatens her by inappropriately touching her.... Yes , no one messes with Bulgur---for he is a truly dangerous psychopath who can kill not just with guns but also with his bare hands....and a 'Bulgur burial ground' is littered with corpses buried by him.... The film clearly rests of the shoulders of Johnny Depp as Bulgur , and Johnny has really waded into the skin of the role . His voice and his appearance exude real menace---and the best scenes of the film are when he warns people against betraying him by threatening them with dire consequences , and then laughing loud and claiming that he was just joking...but nonetheless making sure that he has got his message across.... Johnny's acting is such that even though he is such a psychopath you feel sympathy for him when his near and dear ones die ; these scenes have been directed with skill and show that surprisingly Bulgur has real feelings for his family inspite of his emotionless capacity for murder . So how long will the cozy but unholy alliance between the FBI agent and Bulgur last ?? Will the duo be ever brought to book ?? Watch the movie for the answers.... The film is full of cuss words and use of foul language of which some was blocked out by the censors of my country ( India ) , and the proceedings are grimly realistic---as should be expected of a film based on such people . Other actors act well too , but budget of the film seems to be not-so-high---for special effects are not necessary . Photography and background score are not great though . Verdict---Good .