From a structural point of view, this article has four timelines. One is to show the father's youth experience through diary, one is to show the mother's youth experience through recording, one is the main line: the protagonist Xiao Yuan's experience of searching for his sister in the apocalypse, and the other is a double line, during the same period, the sister Xiao An's experience of waiting for her brother and participating in the apocalypse. The first two lines overlap in the form of children's reminiscences, and the latter two lines overlap in the context of brother and sister meeting and working together in the end of the world. This article focuses on religion and philosophy.