Krystal Jung is a 17 year old girl who had to move to south Korea and live with her older sister Jessica and her aunt Hyorin due to her parents passing away. Krystal is a mute. She can not speak again and can only make rasping noises at the most. At her first day of school Krystal was given a red flag causing her to be the target of everyone. Krystal began to be constantly picked on even by her sister Jessica who is popular. A group of popular teenage boys named Exo soon tries to help her