We never actually meet Annemarie's big sister Lise. She died two years before our story begins. Actually, even in a flashback scene, Lise's clothes appear (Mrs. Johansen is embroidering them), but she does not. Why do you think that is? Shmoop's going to go ahead and guess: Lise is meant to represent something more than she's meant to come out of her shell as an individual character.
Mama and Papa never spoke of Lise. They never opened the trunk [of Lise's clothes]. (2.43)
Lise died in an unfortunate accident shortly before her wedding. After she dies, her family doesn't have the heart to get rid of her trousseau, the chest that contains her wedding dress and the linens she would have used in her new home. (P.S. Lise's trousseau chest shows up at several important moments in the book. Check out our section on "Symbols, Imagery, Allegory" to learn more about it. But don't forget to come back!)
Yes, they hang on to her things, but Mama and Papa refuse to look through it or talk about their oldest daughter. Why do her parents push her memory away? Why can't they bear to look at the things she left behind? Well, if you've ever lost a loved one, you know that it takes time to heal. And the Johansens aren't given that time. After her death, they are faced with another source of loss and heartache—the war.
Only at the end of the novel—after the war has ended—are the Johansens able to open up about their daughter. And we hope that they will able to heal from her death just as they begin to heal from the war, too.
Close to the end of the book, we find out (along with Annemarie) that Lise and the war are more intertwined than we'd originally thought. It turns out the Nazis killed Lise because she was a Resistance fighter like Peter, Henrik, and the Johansens: "'She was part of the Resistance, too,' Papa had explained. 'Part of the group that fought for our country in whatever ways they could'" (17.11). And that's a fight that Peter keeps on fighting, in part as a way of remembering his fiancée.