Kim Hye-in is a high school student from a poor background. She becomes the only witness to the murder of a high school girl. In exchange for her silence on the murder she witnessed, she is offered a chance to study at Cheongdam International High School, the most prestigious high school. There, Kim Hye-in meets Baek Je-na, the leading suspect of the murder and the most powerful student at Cheongdam High. They engage in psychological warfare full of tension and a fierce power struggle.
