That is a very expensive and traditional boarding school for girls.  Moonbyul, Yongsun, Wheein, Hyejin and many other girls come from very different family backgrounds. The first one is the co-leader of a group of girls who are copied by others and feared. The new students  Yongsun and Seulgi soon realize things are not what they seem. What is behind Irene's and Moonbyul's cold actions?  

Irene(from Red Velvet)contacts Solar(from Mamamoo) and asks her help to prevent Seulgi and Moonbyul to be a couple. The 2 leaders end up making a whole mess and includeTaeyeon in the story.