Phoebe wants to know why Sal hasn't told her dad that Mrs. Cadaver is an axe-murderer. Where will Sal go if she loses her dad? She tells Phoebe she will go live with her mom, even though she knows in her heart that this could never happen.
Mrs. Winterbottom is still very unhappy, and Phoebe and Prudence are still completely blind to this. In fact, they get super annoyed when their mom tries to help them figure out their lives and their problems.
Yet again, Phoebe finds a secret message left on the doorstep. This one says, "in the course of a lifetime, what does it matter?" And yet again, Mrs. Winterbottom is totally upset.
As Sal heads home, she realizes that in the course of a lifetime, it matters how you treat your mom. She realizes how shallow Phoebe and Prudence are, and how ignorant they are of their mother's pain.