The 80-year-old Mrs. Monica Bleibtreu has deep piano attainments. Because of the unknown secrets of youth, she has been teaching piano in a female prison for 60 years, regardless of salary or the number of students. After struggling to move a brand new piano to prison, her piano lessons are in danger of being terminated by the suicide of a student. Hannah Herzsprung, the rebellious girl who took the blame, asked to learn the piano, but was rejected by Mrs. Krueger for her rude manners, who played smooth, passionate and presumptuous notes, while the latter found her unlimited musical talent, set harsh conditions to teach her, and forced her to take part in a competition to find talented pianists under the age of 21. Slowly, the music broke through the huge age gap between the two, and their deeply traumatized hearts gradually gained comfort from each other. However, everything was not as calm as it seemed.