In her high-school days, Moon Dong Eun had dreams of becoming an architect. However, thanks to suffering from a brutally violent attack from her bullies, Moon Dong Eun is forced to drop out of school. Years later, the bully gets married, has a child, and attends the same elementary school where Moon Dong Eun now works as the homeroom teacher. After years of plotting, Moon Don Eun begins her plan of revenge against her former bullies and the students who stood by and let it happen.