Seungyeon and Kyuhyun was a lover that had their plan to get married. But Seungyeon can’t make it since she had a cancer and only can survive for a few days. Before her last days arrive, she plans to serenade a sonata to Kyuhyun and she will broke up with him without telling him her illness. But what will happen if she only can give him her serenade since the days were coming to her. Will she give her final serenade?