Kim Hye-In (Lee Eun-Saem) becomes a member of Diamond 6 that rules Cheongdam International High School. She is the first Diamond 6 member to come from a poor family background. Meanwhile, Baek Je-Na (Yeri), the queen of the high school, is in danger of losing an important friendship and the management rights of her father's corporation. Kim Hye-In and Baek Je-Na cooperate and oppose each other for their own benefit. What choice will Kim Hye-In and Baek Je-Na make, who are once again at the center of their desires?