Joyce Tolliver, whose nickname is Muggsy, plays baseball, fights and swears with boys, and is severely punished by her elders. When she grows up, she is disguised as a boy, and sent to live with a wealthy old uncle, Leslie Bolton, who hates women. Her ruse works perfectly until she falls in love. When Bolton e discovers that his supposed nephew is really his niece, he orders her out, but after he realizes that he cannot get along without her, he sends for her to return.