Seong-been Im, Jung-pyo Hong
Eun-kyung Kim, Chang
Beom-soo Lee, Jeong-hee Yoon, Gyu-ri Nam, Beom Kim
On a Saturday, 170 days before college entrance exams, a special class for 20 top students is held at school. But in the middle of class, "For Elise" rings from the speaker and the TV in the classroom shows the top student trapped in a tank of rising water, screaming and struggling to breathe. An unidentified voice asks the answer to a mid-term exam question that will cost her life. Nowhere to run, and only 20 students and 3 teachers are in school. The bloody exams start once again just for them.