My true-crime kick started in earnest with Lacey’s death, but ever since I was old enough to understand what happened to Sarah, I was obsessed with her disappearance. It was the worst thing I could imagine, to have your twin go missing and never come back.
-- Ellery (Chapter 2)

Importance: This quote explains why Ellery is so obsessed with finding the murderer of Echo Ridge. She enjoys reading cold case murder books, but it is more than just an idle pleasure for her. Because her aunt's disappearance tragically pulled apart her family, understanding what happened to her is of the utmost importance to Ellery.

Sadie’s smile in the photo is as blinding as Ezra’s. She was a star back then—the popular homecoming queen, just like Lacey. And she’s been trying to be a star ever since. I don’t know if Sadie would have done better than a handful...
-- Ellery (Chapter 2)