A mysterious noise has been emanating from the upstairs floor for over a month. Eunsu, who has been hearing this noise for an extended period, is experiencing a surge in uncontrollable anger. This has led to her being eliminated from a competition she had prepared for a long time. Determined to find the source of the noise and make amends for her loss, Eunsu decides to write her final piece with the theme of the noise between the floors, hoping that her friend, who is also affected by the disturbance, will assist her in following and tracking down the secret behind it.