Living in surreal universe, Mathilde, a young girl who is studying the violin in a peculiar school, finds her everyday life changed when her hands fuse with her instrument. Panicking, she flees the classroom and unsuccessfully tries to get rid of her instrument. Worried, she attempts to find an exit. However, walking by many other classrooms, she discovers the truth about the place in which she is trapped. Scared, anxious and hunted by the school's authorities, she will finally succeed at getting rid of her instrument and find a door that will take her to the unknown.