In the town of Kurouzu-Cho, Kirie Goshima leads a normal life with her family. One day, as she heads to the train station to meet her fiance, Shuuichi Saito sees her father looking at the alley’s snail shell. Assuming little about it, she addresses the incident to Shuuichi, who claims that his father has been behaving oddly lately. Shuuichi expresses his growing urge to flee the city with Kirie, claiming that spirals plague the city.
But his father’s fascination with form soon proved fatal, launching a series of terrible and unexplainable incidents that led the inhabitants of Kurouzu-Cho to descend into madness.