The film starts as young Kate Barker is brutalized by her father and older brothers, who rape her. Skipping forward 35 years, the middle-aged Kate ‘Ma’ Barker (Winters) now brutalizes innocent people herself.She lives by robbing banks with her four sons; the pragmatic Arthur (Kimbrough), the sadistic Herman (Stroud), the bisexual Fred (Walden), and the loyal, drug-addicted Lloyd (De Niro). It all begins in the late 1920s when Ma leaves her husband, George, and her Arkansas home and embarks on her own with her four sons on a robbery-murder spree to make her own fortune, while keeping them under a tight leash.
When Herman and Fred are arrested and imprisoned for petty theft charges, Ma takes over the group and leads Arthur and Lloyd on a bank robbery spree to gain enough money to get her sons out of jail. The gang is joined by a gunman named Kevin (Dern) who was Fred’s cell mate during his incarceration and, it is strongly implied, his lover. The group is also joined by a local prostitute named Mona Gibson, whom Herman frequented before his imprisonment. The gang resorts to more violent action and robberies.