According to legend, there is a god in the world called Chi. It is everywhere and pervasive. It likes to listen to people's voices at night and attach itself to people to become the opposite personality. Only by changing itself can Chi be defeated.
Zan Wufei is a killer, Ji Yunhui is a doctor, Zan Wufei specializes in killing people, and Ji Yunhui specializes in rescuing people. The two people possessed by Chi met while performing tasks for the opposite side and attracted each other until they fell in love. However, Zan Wufei was Xu Xu since childhood. Allotted to Tang Ruichang, Tang Ruichang was possessed by Chi and became Chi's host. He did many evil things and blamed himself at the same time. Amidst such capricious ideological struggles and personality changes, the three of them were all confused as to where they should go.
Concept: A person has two completely opposite personalities, how would he choose?