Kang Xizhen (Nam Sang-mi), a female college student studying in Seoul, is busy and exhausted every day. One day, she received a call from her mother and learned that her sister Shao Zhen (Shim Eun-kyung) was missing and her whereabouts were unknown. She hurried back to her hometown, but her mother was obsessed and thought that Shao Zhen could return home only by praying devoutly. Faced with her mother's numbness, Xizhen had to call the police, but police officer Taihuan (Ryu Seung-ryong) only treated it as a normal runaway. Soon, a woman hanged herself in front of the window of Xizhen's house and fell to her death. Taihuan found a suicide note in the deceased's room, which even mentioned Shao Zhen's name. Taihuan could not get any clues from Xizhen's mother, so he had to find clues from the community administrator. But he learned that Shao Zhen had been possessed by a ghost, and the whole case began to develop in a weird direction...