The assignment of an idealistic federal agent Eliot Ness (Kevin Costner) to clean up Prohibition-era Chicago leads to violence and manly questions about upholding the law. Initially powerless to stop the flow of booze into the city (the police force is corrupt and everyone in town seems to be on the mob's payroll), Ness finds guidance from an older streetwise cop (Sean Connery, who won an Academy Award for this role) who convinces him he'll need to break some rules if he wants to bring down head mobster Al Capone (Robert De Niro).