One problem is that the Rosens are Jewish, and the solution is for Henrik to smuggle them to Sweden.
The story is set during World War II in Denmark. Denmark is a very small country, so it could not do much to stop the Nazi occupation. This did not mean that Denmark did not fight back. The Resistance helped get Jewish people to safety so they would not be captured by the Nazis and sent to concentration camps or killed.
Annemarie’s friend Ellen is Jewish. Annemarie is old enough to understand that the Nazis are targeting Jews, and that soon it will not be safe to be Jewish in Denmark. She is aware that Sweden is still free, and that Ellen has to get to Sweden to be safe.
"Oh, Ellen," she went on. "You will love it there. It is where my grandparents lived, where Mama and Uncle Henrik grew up. It is so beautiful—right on the water. You can stand at the edge of the meadow and look across to Sweden!" (Ch. 6)
Although everyone is affected by the war, Annemarie is aware that the situation is more serious for Jews. She only vaguely understands the movements of the Resistance. Uncle Henrik and her father talk about fishing, and he says that her mother is going to bring Henrik cigarettes. Annemarie knows there are no cigarettes, and it is Ellen that her mother is going to bring. Henrik will smuggle her to Sweden.
For Annemarie, the knowledge that her friend in danger is confusing and depressing.
Annemarie felt a surge of sadness; the bond of their friendship had not broken, but it was as if Ellen had moved now into a different world, the world of her own family and whatever lay ahead for them. (Ch. 10)
She doesn’t fully comprehend how Ellen and the Rosens will be rescued at first. However, she does contribute to the Resistance effort by playing messenger, because she is young and no one will suspect her. Annemarie learns that she can be brave because she has to be.