Strange Rules: the Non-Existent 804

Shen Yan has been a real estate agent for seven years and has never seen such a house book. The address is No. 804, No. 17, Qinghuai Road, but the old building only has seven floors. Three years ago, his father Shen Jianguo disappeared in this building, leaving only a note: Don't go there at night. Shen Yan originally only wanted to confirm two things. If 804 is a fake house, he will call the police to cancel it. If 804 really existed, he wanted to know if his father was still trapped in it. At 23:58 that night, he saw his name on the doorman's registration form. Name: Shen Yan. Visiting room number: 804. Entry time: 23:58. At three o'clock in the morning, the out-of-service elevator opened the door by itself, and there was an extra polished 8 in the button. At the end of the corridor on the eighth floor, there is a House Rules under the door of 804: First, don't trust the people on the eighth floor. Second, don't turn on the kitchen faucet after three o'clock in the morning. Third, if someone calls your name outside the door, don't answer. Before Shen Yan finished reading, his father's voice sounded outside the door: "Xiao Yan, open the door."