A heavenly maiden loses her winged robe beside a mountain waterfall. A lonely woodcutter hides it. What begins as an old folktale soon descends into something far darker. Rejected by heaven after lingering too long in the mortal world, Seorin falls into modern Seoul—a city of neon lights, subway tunnels, sleepless strangers, and endless loneliness. As strange deaths begin spreading through motel rooms and underground stations, whispers grow about a pale woman whose presence leaves men trembling between ecstasy and terror. A detective obsessed with the case follows her trail through rain-soaked streets and forgotten alleys, only to discover that Seorin is no simple killer. Something hungry has awakened inside her. Something born between heaven and humanity. As ancient forces descend from the sealed gates above the clouds, Seorin must confront a terrifying truth: Some forms of loneliness can open doors that should never be touched. Blending Korean folktale imagery with psychological horror, urban fantasy, supernatural noir, and tragic romance, Feathers Beneath the Neon Sky reimagines the legend of the heavenly maiden as a haunting descent into desire, possession, and the fear of abandonment.