Messud’s sixth novel is the story of Cassie and Julia, best friends from nursery school until seventh grade. For Julia, who narrates their experiences, the two are as close as sisters, though their families fail to mesh and the differences between them grow more apparent over time. Without Julia to set limits and question plans, Cassie veers into potentially dangerous emotional territory, especially when she decides to track down her father, and Julia begins to see how her notions of “home” and “love” were never Cassie’s. Writing with the elegant, meticulous prose that made the characters of The Woman Upstairs and The Emperor’s Children so vivid, Messud explores the intricate psychology of adolescence and the limits of friendship.