Xu Qingqing (played by Guo Biting)'s mother left with someone else, leaving her to live with her father. She runs an old watch shop independently. One day, a boy named Cai Zihan came to repair the watch. Qingqing recognized him because he had slept at the door of her house before. The shy boy came to Qingqing to repair the watch for several days. He finally plucked up the courage to tell Qingqing that he was her junior high school classmate. Qingqing also knew from the words that the boy liked her. Zihan has not appeared since the last time he went to the mountain waterfall until Qingqing called Zihan's home. Zihan's parents actually told Qingqing that their son was dead. When Zihan appeared again, Qingqing wanted to go to his home, and he really took him to his home. Zihan's parents told Qingqing that after Zihan died, Baiyu suffered from schizophrenia, and he would become Zihan every day after three o'clock. Zihan's parents are about to move away, and Baiyu will return to his parents in the United States. Qingqing was worried that she would never see Zihan again, and she finally stepped on the train that she had not dared to take for many years...