Won-woo, living with a grandma and mom, is alone at school because of her narcolepsy, however, she still is vigorously a dreaming girl for her mom. One day, she happens to join a group for a school project with Jun-seo who has teased her as a sleepyhead, as Jun-seo teaches her how to operate a camera and ride a bicycle, she opens her mind and feels close to him. Whenever the moment of her falling asleep is a desperate incident, she always endures the moment of dreaming in hearing to a whistle sound. As she wakes up, the whistle sound goes away, by the way, whose sound is it anyway?

(Source: http://www.koreanfilm.or.kr)