Nuclear winter swallows the earth and civilization sinks to the bottom of the sea. The 13 deep-sea city-states and the "N. O. A. Noah" federation control the thoughts of all survivors. In order to eliminate the pain, Noah is gently promoting the fusion of consciousness, turning everyone into a "sea" without borders. Lin Zhan, a lonely policeman awakened from the civilization of the past, unexpectedly maintained his independent personality. He can feel pain, and therefore he can hold his own. And pain, in this world, is seen as a mistake that needs to be erased. Elsa, the only girl who retains her original body and refuses to connect with consciousness, is the true "proof" of humanity. In the deep sea order where their names, emotions and memories have been erased, they will use the last boundary to fight against the gentle assimilation under the eternal night. If the self disappears, will human beings still exist?
