Isola writes to Sidney. She's very happy that he's coming to look at Granny Pheen's letters; she thought the sub-editor was nice but uninteresting. He did, however, introduce Isola to Miss Marple, a character from mystery books who solves crimes by using her knowledge of human nature. Isola promptly borrowed Miss Marple books from Amelia and has decided to train herself to solve mysteries—not that there are any on Guernsey. Isola says that Eben is having a beach party when Sidney is here and Sidney's invited. There's supposed to be a happy announcement at the party. Isola hopes that Eben isn't getting married, as she believes a wife wouldn't let him continue with the Society.
Even though Isola is flouting conventions by living as a spinster and making elixirs, her comment about Eben possibly getting married indicates that she still holds a number of very traditional ideas about marriage and how married people relate to each other. Isola's introduction to Miss Marple offers her another way to make sense of the world around her by paying closer attention, illustrating again that books can help people see their world differently.