In the 1990s, in a small town by the Yangtze River, the rebellious boy Zhao Xiaolong (played by Li Xian) met his beloved girl Dongdong (played by Gu Xuan) and her good friend Xiaomei (played by Zhang Qiyan). With the initial intention, he went through the wanton and flamboyant youth with several friends: Fangyuan (played by Dong Boyui), Dasi (played by Lin Xiaofan), Sanpi (played by Liu Weibo), Wuyi (played by Li Zonglei). This period of youth finally came to an abrupt end because of Dongdong's disappearance. More than a decade later, when the brothers were all blurred and heading towards middle age, only Xiaolong was still stubbornly asking for an explanation for Dongdong's whereabouts. At the party, the four people who had entered middle age recalled the past, but Xiaolong suddenly forced Dasi to tell the truth about Dongdong's "disappearance". The dusty "truth" made them unable to reach their hearts forever...