The Doorway to Hell on AllMovie

In this early talkie, a vicious crime lord (played by Lew Ayres in a rare villainous role) decides that he has had enough and much to the shock of his colleagues decides to give the business to his second in command (James Cagney in hi second film role) and retire to Florida after marrying his moll. Unfortunately, he has no idea that she and Cagney are lovers. Part of the reason the don wants to leave is to keep his young brother, who idolizes him, from learning the awful truth about his avocation. Soon after moving down to Florida, former rivals kidnap the brother and kill him, causing the reformed gangster to come back for deadly revenge. This was an innovative film and featured a lot of elements that would become standards in the gangster genre including tommy guns carried in violin cases, terrible shoot-outs, and lots of rum-running rivalry.