Xiao Dou is a shy and naive mailworker living in Beijing with his sister. When a coworker is fired for reading people's correspondences Xiao Dou takes over the same mail route. He soon finds himself indulging in the same curiosity, eventually developing an obsession. Xiao Dou chooses to spend time reading letters instead of socializing with friends or coworkers. As he becomes increasingly tied to the letters, he begins to intervene in the lives of those who write and receive the letters.