Although the primary story of The Nightingale is indeed a flashback from Isabelle's young adult years, Hannah often utilizes flashbacks within Vianne and Isabelle's narrative to further contextualize their characters and situations. For example, in Chapter 5, the narrator briefly flashes back to Isabelle's childhood as she recalls being separated from Vianne at age four:
The long train ride… Isabelle stuffed in beside Vianne, who did nothing but sniff and cry and pretend to sleep. And then Madame looking down her copper pipe of a nose, saying, They will be no trouble. Although she’d been young—only four—Isabelle thought she’d learned what alone meant, but she’d been wrong.
From this passage, readers gain context for Isabelle and Vianne’s tortured young relationship, discovering that the two sisters' parents abandoned them at various stages of their childhood. In this particular instance that Isabelle recalls, Vianne and Isabelle must separate after Vianne becomes pregnant and Isabelle is forced to attend boarding school. Isabelle remembers this moment as one of genuine heartbreak and isolation. Even at the extraordinarily young age of 4 and then 7, Isabelle learns to expect abandonment from others. In the novel, flashbacks often appear to provide further context for characters' motivations, desires, and relationships. Hannah cannot devote entire chapters to this type of background—such choices would likely stall the fast-paced, forward-moving narrative—but she can pause and utilize the device of a flashback to provide important details and also to explore how memory influences the lives of Isabelle and Vianne.