Gangstress Ma Parker and her fiendish brood--sons Pretty Boy, Mad Dog, and Machine Gun and daughter Legs--have invaded Gotham City and begin their wave of crime by disrupting Gotham's Ladies Auxiliary's Mother of the Year Awards Ceremony and robbing the entire audience. Batman and Robin are called into action. They quickly locate the fiendish family at their home on Cherry Blossom Road, where, under the cover of a smoke bomb, they evade apprehension, save for Pretty Boy. Later, Machine Gun is also captured, after The Parkers pilfer money from a theater's box office. Then Mad Dog is foiled in his attempt to hold up a drugstore. They finally trace Ma and the last of her delinquent children, Legs, at an old ladies' home, where, after Ma's high-speed rocket-wheelchair race ends at a well-placed wall, they are arrested. The Caped Crusader and The Boy Wonder quickly take Ma and Legs to Gotham State Penitentiary to join the rest of their family.

As Batman and Robin leave the prison, they notice a trustee examining The Batmobile's Batengine. Writing off his rather suspicious behaviour as curiosity, they start on their way. Unfortunately, back in Warden Crichton's office, Ma reveals that she has been secreting sympathetic guards into the prison for some time, so it is easy for her gang to take over; she also brags that Batman was her unwitting pawn in capturing her and her crooked kids, for now she's in total control of The Gotham State Pen! Furthermore, unknown to The Dynamic Duo, that "curious" trustee planted a timebomb inside The Batmobile, thus it has been rigged to explode once it reaches 60mph!