7pm, October 13, 2011
The film is set in a high school, where an elite group of twenty students—including rebellious heroine Kang Yi-na, her timid best friend Yoon Myong-hyo, and her would-be boyfriend Kang Hyeon—are taking a special class for their college entrance exam. After Kang Yi-na is nearly strangled and another student throttled in the restroom, the classroom TV screen switches to an image of top-ranking student Hye-yeong trapped inside a fish tank that is slowly filling with water. A disembodied voice announces that her life depends on the exam questions he will set for them, and that a student will die for every question the class gets wrong. Trapped with the students are head teacher Hwang Chan-wook and English teacher Choi So-yeong. Yi-na realizes that the students are being killed in order of their rank in the class, and she is ranked fifth. Someone is slowly killing the students one by one, but who are they? And what do they want?