This film tells the story of the third baby boom in Chinese mainland in the1980s. Many couples only had one child in response to the family planning policy. Cao Depei (Li), a middle-aged Beijing photojournalist, and Duan Jinghua (Song Dandan), a beautiful young wife, were among them. They and their five-year-old son Han Han formed a happy family of three. Cao De Peiren is about to reach the climax of his career, and his film festival is being planned.
One day, Cao Depei received a phone call and asked him to go to the Children's Welfare Institute to bring back his son, unknown so. After coming to the welfare home, he met a silent boy in his 10 s. He came to Beijing to find his father with a letter, which he wrote to his ex-wife in Northeast China. He met his ex-wife when he jumped the queue in the countryside, and she has been there since the divorce. In order to find out the truth, he took the boy to the northeast.
Through the mouth of his ex-wife's later husband, Cao Depei learned that his ex-wife had passed away, and she was pregnant when they divorced. This boy named Zhao () is indeed his son. At that time, Cao Depei wanted to leave Xiao Mu in the northeast, but he followed him on the train. After arriving in Beijing, Cao Depei put Xiao Mu in a darkroom in the basement and asked him to develop the photos. After struggling to explain everything to Duan Jinghua, he was told that he was pregnant, but he seemed to have no intention of asking about the photo exhibition.