After the Countdown Reached Zero, I Became Part of the Door

At two o'clock in the morning, three people died in the elevator. Cheng Yan lived in Building 7, and he heard a knock on the door. The woman outside the door was shaking all over: "There is something in the elevator... It followed me up..." Cheng Yan could see the death countdown above everyone's head. His own: 47 hours. The woman's: 4 minutes. After four minutes, she will become part of the Door. Before her death, grandma left him a black umbrella with a warm handle - but grandma had been gone for three years. Cheng Yan later learned that grandma had guarded that door for thirty years. Now, it's his turn.