Tong Zhi, a fourth-year veterinary student, has a crush on Gu Bin, a landscape student from Taipei. She never had the courage to confess, and for the past four years, she wrote all her feelings into unsent letters. With graduation approaching, an unexpected mailing makes Gu Bin misunderstand her intentions, making him think that she likes his good friend instead. As it turns out, she is not the only one who holds secrets and cannot confess. Will she succeed in confessing? A story spanning between two eras and the two cities of Guangzhou and Taipei kicks off.