Nara and Hyomin. Hyomin and Nara. Both of them are best friends since they were babies. They like to play with each other everyday. Some of them thought they are siblings but no, they are not. Lee Hyomin and Kim Nara grow up together. When they are six, Hyomin slowly becomes deaf and blind. On her birthday, she is completely blind and deaf. She can't see or hear anything. She is living in darkness. For years, she lives with her white cat, Fluffly and Nara as their parents died from a car accident. Nara always bring Hyomin everywhere because she is scared of the 1001 possibilities that could affect Hyomin's life.

Cha Eun-woo is Nara's best friend and senior. He is a member of ASTRO and despite busy schedules, he will pay Nara a visit and sometimes, he brings s along. Eun-woo never know who is Hyomin, until one day...