Seven-year-old little sheep Miemie wears the blue bell left by her grandma and is swept by a whirlwind into the color-fostered, fading Foggy Valley, where people forget their names and shadows disappear. Transforming into a little detective, Miemie befriends Naonao the straw rabbit, Dingdang the tin kettle, and Dandan the little lion, tracing the mysterious shadow that steals colors following the Song of the Rainbow. Everyone unveils the secret: the shadow is Grandma's shadow Huihui, isolated by the Rainbow Gate, who stole colors out of fear of being forgotten. After enduring trials and reaching reconciliation, the companions restore the rainbow gemstone. Foggy Valley regains its colors, and the Rainbow Gate opens. Miemie bids farewell to her companions and returns home, realizing that remembering and companionship mean protection.