In the shadow of the city where supernatural phenomena occur frequently, Qi Yichuan, the mysterious captain of the supernatural task force, has been guarding the balance between the human world and the spiritual world alone for a long time because of his ability to live forever. What the years have left on him is only endless vicissitudes and compassion for life.
Xiheliu was originally an ordinary person, but because he was possessed by an evil spirit at birth, he was troubled by nightmares since he was a child and suffered from headaches as an adult. The opening of his yin and yang eyes made him involved in a bizarre and supernatural world. An accidental encounter and the thread of fate tightly entwined him and Qi Yichuan.
Qi Yichuan accepted Xiheliu as his disciple, ostensibly to get rid of the evil spirit hidden in his mind, but the cruel truth was that the only known way would cost Xiheliu his life. With complicated emotions, Qi Yichuan carefully taught Xiheliu various self-protection abilities so that he could survive in this dangerous supernatural world; at the same time, he searched around, eager to find a way to have both sides, which could not only save Xiheliu, but also eliminate the evil spirits.
During countless days and nights fighting side by side, and in the process of facing one terrifying and supernatural incident after another, the two gradually grew closer to each other. From the initial relationship between master and disciple, a different kind of love gradually developed. But the evil spirit hidden in the darkness is ready to move. Not only do they have to face various threats in the supernatural world, but they also struggle with emotions and life and death choices. Can they find a way to break the situation in this dangerous supernatural world?
