IESB reports that whilst speaking with "King Arthur" and "Training Day" Director Antoine Fuqua, he revealed he will be working on a prequel to Brian DePalma's 1987 hit "The Untouchables" which told the story of Al Capone and adversary, Elliot Ness.
According to Fuqua, the film will take place years before law-man Ness (played by Costner in the former) and gangster Capone (played by De Niro) ever crossed paths and focus solely on a young Al Capone. Sean Penn is being sought to play the young Capone.
There's also talk of both a prequel and a say to "King Arthur", says the site, but Fuqua isn't attached to either."
Thanks to 'KarlChilders'
