At 11:50 in the night, Shen Shen found a yellowed note in an abandoned apartment: "Do not respond to any sound after 12 o'clock in the morning." But there was a knock on the door from his sister who had been dead for three years. The awakened "rules" system emerges - he can see weird rules invisible to ordinary people, at the cost of losing one point of sanity every time he cracks a rule. When the residents of the entire building begin to follow twisted rules, Silence must find the truth before his sanity returns to zero. Is my sister a ghost, or does she have another secret? What indescribable existence is hidden behind that door?
