What is the setting for the story? What are two pieces of evidence that show that the time and place is important to the story?

Louise, the narrator of this novel, lives on Rass Island, and she is thirteen years old in 1941. Much of the book takes place during World War II. Both the setting of the island and the time period convey a sense of isolation that echoes Louise's feelings of loneliness, as she lives in the shadow of Caroline, her beautiful and talented twin sister.
Both twins learned piano while young, but Caroline soon emerged as the more gifted piano player and singer. This phenomenon, as well as Caroline's brush with death when she was born, has caused Louise to be frequently overlooked. Early in the novel, Louise quotes Caroline: " 'I haven't got anything to do but practise this summer, so I've decided to write a book about my life. Once you're known,' she explained carefully as though some of us were dim-witted, 'once you're famous, information like that is very valuable. If I don't get it down now, I may forget.' She said all this in that voice of hers that made me feel slightly nauseated." This quote captures the difference between the two twin sisters; Caroline feels she has a story to tell the wide world, one that the world will surely be interested in reading. In this way, Caroline expresses her ambitions that go beyond her current life on the island. Louise feels like she holds "a very minor role" in her twin's story, one that makes her feel lonely and unappreciated.
The war plays a significant role in the relationship between the twins. When the news breaks that the Japanese have bombed Pearl Harbor, Louise takes the report hard and embarrasses herself in class. When Caroline finds her, tearful and humiliated, Louise expresses her emotions with a desire to leave the island; she says to Louise in response: " 'Well, you can't run away tonight,' she said. 'There's no ferry until tomorrow morning. You might as well come in and have supper and get warm.' " Caroline's matter-of-fact tone contrasts powerfully with the warmth and emotion of Louise's experience. As the war intensifies, the conflict between the sisters deepens as they manage their fears and stresses very differently.