Those movies just won't stop!
Tom Hardy plays 2 main heroes of the story - brothers, gangsters, London mobsters. Eventually - both arrested, but not before they did some pretty grim things. However, this movie is not exactly a gangster movie, as you may think from the trailer. It's more of a drama, dealing with mental illness, suicide, abuse and stuff like that.
Here's the article on how true this is. And it seems like a lot was made for the Hollywood effect. Like Ron speaking openly about his homosexuality, or about Violet being mean to Frances... This movie just ups the drama when it needs to. Also, some facts about murders are still unclear, it seems, so movie offers their own justification which may or may not be true. So, while the general idea and final result may be true, the inner story should be taken with a grain of salt, I guess.