Zhang Zhiyu, a 30-year-old pianist, fell into a low point after failing to win an international competition. When he returned to his hometown to relax, he unexpectedly became a substitute music teacher in a village primary school. Here, he met Sun Shiyu, an 8-year-old girl who went to the countryside with her grandfather. With her smart eyes and love for music, the two gradually bonded over a four-hand song and a kitten named "Missing". When leaving, Sun Shiyu asked Tong Yanwuji if he would wait until he grew up, but Zhang Zhiyu solemnly agreed.
This wait is twelve years. Sun Shiyu returned to China with a doctorate in mathematics. She reunited with Zhang Zhiyu, a well-known musician, at her best friend's birthday party. She had long forgotten her childhood promise, but Zhang Zhiyu was filled with low self-esteem due to the age difference and past obsessions. It wasn't until the piano accompaniment of the Mid-Autumn Festival Gala and the oil painting of "Girl Holding a Cat" in Zhang Zhiyu's home that her dusty memories were awakened.
However, this love that spanned time was repeatedly hit hard due to the strong opposition of his grandson, who forced him to separate and send him abroad. However, Zhang Zhiyu always kept his promise and waited for the most cherished "cat" in his life like he was guarding his "misses". This fateful relationship, which hides warmth in the midst of abuse, has become stronger and stronger over the years.
