To shoot a viral episode, five young people move into a seven-person house deep in the mountains of western Hunan. The landlord leaves behind only a printed sheet of paper listing seven mountain rules: break one, and one person disappears. On the first night, a companion becomes six people on camera. The next day, the villagers claim that this person never existed. Reporting it to the police, checking surveillance footage, and searching the ancestral hall—all paths lead to the same answer: "He left on his own."