Divine Research Institute subconscious therapist Tian Mai, in order to save her trapped master, actively deep-dives into the mental labyrinth of severely comatose patient Lin Xingxing. Here, death rules are nested layer by layer, and monsters are all objectifications of traumatic memories—once a rule is broken, consciousness will be permanently locked. Tian Mai does not blindly follow or hard-fight, instead taking advantage of rule loopholes to counter-kill monsters, yet when dissecting the source of trauma discovers the erased "fifth person" murder case, as well as the fire cold case of her parents who died in the line of duty fifteen years ago. When the secondary personality appears and the truth approaches, can Tian Mai, while saving the patient, walk out alive from her own past?