Young Kate Barker is brutalized by her father and older brothers, who rape her. Thirty-five years later, the middle-aged Kate 'Ma' Barker, now brutalizes innocent people herself, while indulging her monstrous sexual appetites. She lives by robbing banks with her four sons; the pragmatic Arthur, the sadistic Herman, the bisexual Fred, and the loyal, drug-addicted Lloyd. 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.