In an episode which introduces Mildred's sister Agatha to the cast (Nancy Walker had already committed to her own series for the following season, and Agatha was to become the new housekeeper), the McMillans, Mildred and Agatha go to visit a woman relative of Mildred and Agatha, a very wealthy woman who's dying -- but not quickly enough to suit one of her nephews, who's in debt to a loansharking company later described as "just this side of Murder, Incorporated." Threatened with death if he doesn't come up with the money right away, the nephew smothers the old lady in...