Twenty years ago, Yoon Hwa Pyung, a young psychic born into a shaman family, learns about the powerful demon called "Son" (Guest). The demon possesses the power to control other demons and allow them to possess weak people. The possessed people then go mad, kill their families, and stab themselves in the eye. Hwa Pyung, Choi Yoon; a young boy born in a religious Catholic family, and Kang Kil Yeong; the daughter of a detective, fatefully meet when their families are killed by a demon.
Twenty years later, the demon killings started again. Hwa Pyung is now a taxi driver who uses his power to seek out possessed people in order to help them, Yoon is a Catholic priest who is talented in exorcism, and Kil Yeong is a detective who doesn't believe in ghosts. The trio meets again and tries to work together to defeat "Son".