Della brings over Priscilla Prudence, a witch who has lost touch with the way things have changed since her day back in 17th-century Salem. Sabrina tries to introduce a baffled Priscilla to the hip, happening ways of the '70s.
After Aunt Hilda yells at her for doing good deeds, Ambrose lets Sabrina in on her aunt's "secret vice": every time she does evil to someone who deserves it, she's in such a good mood that she can't help sharing her joy by doing a good deed for someone else.