Gu Yan is the captain of the Criminal Investigation Detachment of the Municipal Public Security Bureau. He has recently become obsessed with an online suspense novel called "Darkness". However, when ten chapters were about to be completed after the author was announced, news of the author's death spread throughout the Internet and the book was no longer updated. Half a month later, Gu Yan suddenly discovered that there was a very strange website on the Internet that continued to serialize "Yinhei". The domain name was a foreign website. At the same time, many secret room murders occurred in the city, and the victims all had one characteristic in common - they had their computers on before they died, and the computer pages were all stuck on the latest serialized page of "Darkness".
Gu Yan filed a case and prepared to investigate the matter personally. At the same time, the Criminal Investigation Bureau of the Ministry of Public Security suddenly arranged for three young people (Fu Li, Hong Qifeng, and Zhao Qianyue) to assist him in investigating the matter. At this time, an invitation letter was sent to the bureau, inviting Gu Yan and three young people to an English-style villa in the suburbs, saying that it would let them know about multiple secret room murder cases. Unexpectedly, Gu Yan was knocked unconscious in the villa when he went with Fu Li, Hong Qifeng, and Zhao Qianyue, and when he woke up, he had traveled to the world in the book.