Ma Barker and sons Mad Max, Machinegun Nonong and Pretty Boy Fredo want to be the number one criminal family in the land. They think this is going to be their ticket to fame and fortune. But plans go awry when Pretty Boy falls in love with Sheila, a pretty young lounge singer/owner. It turns out that she is the grandaughter of Don Vito , the family's main competitor. Don Vito learns of the relationship and decides to hit two birds with one stone. He sets up Ma Barker and her sons as the fall guys of their criminal operations hoping Pretty Boy will voluntarily leave his precious grandchild alone. But Pretty Boy learns of the plot against his family. His only hope is to convince Shiela of her grandfather's evil ways and help her get him arrested.