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