Eliot Ness and the Untouchables are in Florida to arrest Ma Barker and her sons who are staying at a holiday motel under assumed names. With the aid of the State Police, they stage a raid but the well-armed Barker gang hold them off for over 6 hours. Years before, Ma Barker's sons had developed quite a reputation as petty criminals but her real career in crime started when one of them, Herman, was shot by a policeman during a break-in. Soon the Midwest is in the midst of a crime spree that included kidnappings and robberies. The family starts to fall apart when one of her sons, Doc, decides to get married. He leaves home but used currency from a kidnapping and Ness is soon on his trail. Ma Barker gives their location away leading to Ness' raid.
—garykmcd