In Lincheng, memories can be extracted and sealed like commodities. Lin Zhou is a top "memory submariner". His job is to sneak into the sea of consciousness of his clients and remove those painful islands of memory. One day, a mysterious woman named Su Yin came to the door with a simple request: forget someone. However, when Lin Zhou dived into her seemingly calm sea of memory, she discovered that there were turbulent undercurrents under the sea. The isolated island she wanted to forget was not only the source of her pain, but also a beacon, guarding a truth that could subvert everything. In this game with forgetfulness, Lin Zhou was forced to face his dusty past.