The plaster wall in Sal's living room in Bybanks is very important. Yes, that's right: very important symbol alert! It is such a delicious symbol that we don't want to unpack it too completely for you. Discovering what it means and how it contributes to the story is an exhilarating process of which we don't want to rob you, awesome reader.
However, we do want to call your attention to a few different moments and ask a few questions.
We first hear about this wall in Chapter 1, at the very beginning of our journey with Sal, and it stays in the back of our heads throughout the novel. Here's what we hear about it:
My father started chipping away at a plaster wall in the living room of our house in Bybanks shortly after my mother left us one April morning. Our house was an old farmhouse that my parents had been restoring, room by room. Each night as he waited to hear from my mother, he chipped away at that wall.
On the night that we got the bad news—that she was not returning—he pounded and pounded on that wall with a chisel and hammer. At two o'clock in the morning, he came up to my room. I was not asleep. He led me downstairs and showed me what he had found. Hidden behind the wall was a brick fireplace. (1.13-14)
What does it mean that there is a brick fireplace hidden behind this wall? How does Sal feel about this discovery? How does her dad feel about this discovery? What else does this discovery make Sal remember?
Then, at the end of her story, Sal tells us that she begins to understand why her grandparents took her on the road trip to find her mother. In fact, she begins to understand a whole ton of things about the last year or two. She tells us:
[L]ately, I've been wondering if there might be something hidden behind the fireplace, because just as the fireplaces was behind the plaster wall and my mother's story was behind Phoebe's, I think there was a third story behind Phoebe's and my mother's, and that was about Gram and Gramps. (44.2)
Oh now this is interesting, isn't it? Perhaps that plaster wall that we heard about all those chapters ago represents the stories that are buried within other stories and how these stories give rise to new stories. Just as someone once decided to build a plaster wall over the fireplace in Sal's home, Sal can choose to build something of her own, something new in her life. However, in building something new, it doesn't necessarily mean that she has to get rid of the old (like the fireplace). Her memories will stay with her deep in her heart just like that fireplace stayed hidden behind the plaster wall.
Perhaps there are more stories hidden behind the plaster wall and the fireplace. Maybe as we read this story, we chip away at ourselves, too. We just might find our own stories hidden within Sal's, and we might have realizations and discoveries of our very own.