The terms of her father's will tie Joyce to her Aunt Evelyn until she is 25 - or Evelyn will inherit the entire estate. But Joyce wants to marry Leslie, and the money she will eventually inherit would be a considerable help to him in his career.
Aunt Evelyn is a violent drunk, and one evening Joyce speculates to Leslie that if she fended of one of her aunt's violent attacks and her aunt died of 'one of her heart attacks' she could hardly be held accountable - could she?
Leslie isn't really sure. And the next day Aunt Evelyn dies suddenly.