When Gu Linyuan rented a room in Qinghe Apartment at a very low price, he thought he had gotten a big deal. However, from the moment he stepped through the door, he completely lost contact with the outside world. Outside the window is an eternal thick fog, the mobile phone signal is permanently interrupted, and the only guide to survival is the yellowed "Qinghe Apartment Resident Rules" nailed to the back of the door.
