In a high-end residential area in a bustling metropolis, there lives a couple. The woman is Li Wandou (played by Ying Caier), a popular suspense novelist. Her boyfriend Ding Chaoyang (played by Zhang Duo), a white-collar elite, had been married before, but his wife mysteriously disappeared 5 years ago and her whereabouts are unknown. There is a room in his house that has never been opened, and Wandou is absolutely forbidden to approach it. One day, their doorbell rang, and looking out through the door mirror, there was a terrifying woman with black hair, white clothes, blood-red nails and a weird smile standing outside. The strange events intensified, and Wandou's life was shrouded in a huge shadow. When her boyfriend refused to move, she began to try to explore the reasons behind this series of events on her own. The strange woman living downstairs, the little security guard who was hesitant to speak, and the door that had never been opened, the truth of all the secrets slowly surfaced... This film is adapted from Lian Jian's thriller novel of the same name.