Xiao Zhiyu and Hu Xiu are brought together by a Republic of China-themed murder mystery game. In the scripted NPC game filled with falling snow and spies in the shadows, the two ignite a fateful spark. An unexpected reunion in the real world reveals the mystery of each other's identities. The two shuttle between the misaligned time-spaces of reality and the script, and finally achieve two-way growth in the cross-dimensional bond, completing the transformation of love and self.

Set in a Western-style house in Shanghai's French Concession, the film spans decades of change. Once home to the Lin family, the house is transformed into a maternity hospital in the 1930s, then a factory in the 1950s after the founding of the People's Republic of China. By the 1990s, it becomes a mixed-use building, with each era bringing new stories of the people passing through its doors.

Criminal police Li Hongqi accompanied his girlfriend back to his hometown for the Chinese New Year, and accidentally discovered that his father-in-law was involved in this crime-related case. With a strong sense of justice, Li Hongqi decided to give up his vacation and cooperated with the local police to start an investigation.