Every last Thursday of the month at an all-girls high school, the students of Class 2–5 cast their votes in a popularity poll. The results classify them into Grades A, B, C, D, and F. If they fall into Grade F, they become legitimate victims of school violence.

The series follows the bittersweet relationship between a banchan shop owner whose daughter enters the war of Korea's college entrance exams, and a top hagwon instructor.

In Daechi-dong, a prestigious neighborhood fueled by academic obsession, desperate students turn to a forbidden stimulant to boost their exam scores. Instead of academic success, the drug unlocks a terrifying side effect, forcing the children to hear the whispers of vengeful spirits. As the community transforms into a hunting ground for evil forces, an exorcist priest named Antonio must risk his soul to save the possessed students.