Jo helps out Cathy and Steve Schwartz with their four daughters: 6-year-old Samantha, 4-year-old Amanda, 3-year-old Katelyn, and 1-year-old Emily. Cathy's sister, Donna helps care for the girls while Steve and Cathy work full-time. Discipline is non-existent in the house, Cathy struggles to get her two oldest daughters off to school on time, and Katelyn is not even potty-trained yet. Cathy thinks that the girls consider Donna more of a mother to them than she is. Donna is resistant to change and doesn't even want Supernanny around. Can Jo change Donna's mind and help the Schwartz family?