Lundi is a young boy who lives with his aunt and uncle in Switzerland in the early 1930s. One day while walking around the Alps, Lundi finds a little girl who is the only survivor of a plane crash and has lost all her memories. She is named Jeudi by his uncle and both of them are raised together. As they grow up together, Jeudi and Lundi develop a deep friendship for each other. A few years later Jeudi wants to find her past. Her only clue is a song that she is constantly hearing in her head, a song called Alpen Rose. At the time of World War II, Jeudi and Lundi set on a journey to discover Jeudi's past and in the process learn the depth of the love they have for each other.