 A meek middle-aged spinster, down-trodden by her two older sisters at home, makes a sentimental visit to the big city to see the boxer son of her long dead childhood beau. There she finds him falling victim to the fight rackets, and is herself caught in the crossfire between rival gangsters, who mistakenly believe that she is the eponymous head of the notorious Ma Parker gang. Teaming up with a sports reporter juggling his work and his love life, she employs her own unique blend of naive innocence and no-nonsense realism to see that everybody gets their just deserts, herself included.