Lundi is a young boy living with his aunt and uncle in Switzerland during the early 1930s. One day, while wandering through the Alps, he discovers a little girl who is the sole survivor of a plane crash and has lost all her memories. His uncle names her Jeudi, and the two are raised together. As they grow up, Jeudi and Lundi develop a deep friendship. A few years later, Jeudi wishes to uncover her past. Her only clue is a song she constantly hears in her head, titled Alpen Rose. During World War II, Jeudi and Lundi embark on a journey to discover Jeudi's history, and in the process, they learn the depth of the love they share.