In a small South Korean village, a series of bizarre and violent murders begin to take place, creating panic among the residents. The unexplained deaths coinciding with the arrival of a mysterious Japanese stranger lead the villagers to suspect that he is somehow involved. Jong-goo, a local police officer who is both inept and cowardly, is drawn into the investigation as the situation grows increasingly dire. His personal stake in the matter escalates when his beloved daughter, Hyo-jin, exhibits strange symptoms and behavior, suggesting that she might be caught up in the supernatural occurrences plaguing the town.

Seeking answers, Jong-goo encounters a variety of characters including a shaman, Il-gwang, who is hired to conduct an exorcism; a woman known as the "Mudang," who provides cryptic warnings; and the enigmatic Japanese man, who lives in seclusion in the forest. Despite warnings to stay away, Jong-goo's desperation to save his daughter leads him to confront the perplexing and frightening events head-on. With his incompetence as a policeman juxtaposed against his determination as a father, Jong-goo struggles to unravel the mystery that threatens everything he holds dear, plunging him into a labyrinth of suspicion, paranoia, and ancient folklore.