After 18 months of hard work by Eliot Ness and the Untouchables, Al Capone is convicted of tax evasion and sent to prison. It's only the start however for the law enforcement officers as Capone has left a fully functioning mob empire intact. Soon however, Capone's top enforcer, Frank Nitti, is eliminating some of his competition for control of that empire. In the process of fighting Nitti, Ness recruits a new member of the squad, one-time barber Enrico Rossi who had volunteered to testify against the crime boss after witnessing a shooting. Nitti's main competitor for Al Capone's empty chair is the mob's bookkeeper, Jake Guzik. Ness' plan is to create a rift between the two by focusing on Nitti's personal holdings and leaving the others alone. Guzik proves to be a far more intelligent opponent than Ness may have given him credit for so he tries to get a dead mobsters wife, Guzik's niece, to inform on the bookkeeper.