The story revolves around a private investigation agency called "Urban Secret Service". The firm's investigator Gu Yuan, with the assistance of technical consultant Shen Qing and police officer Li Mu, investigated a series of seemingly ordinary urban ghost stories, but found that there were deeper reasons and connections hidden behind these ghost stories. As the investigation deepens, they gradually uncover another side of the city - a "parallel city" composed of various anomalies and unknown forces. At the same time, freelance writer Su Wan is also secretly pursuing the same truth. She and the members of the firm are both enemies and friends, and together they face the threat from the "parallel city". The story has multiple parallel lines, and each character gradually grows up in different events, and finally comes together to fight against the crisis that threatens the real world.
