In a small town in Japan, Kirie comes upon her boyfriend's father silently videotaping a snail. He seems unaware of her presence and she thinks no more of it. Later, the man's obsession with spirals becomes more and more bizarre, which drives him to suicide.
Soon other inhabitants become possessed with different forms of spirals, one student seems to be mutating into a snail, another's hair becomes strangely medusa-like.