n the eve of the dreaded university entrance examinations, the lives of 24 of the smartest and brightest students at one high school, are on the line. Locked inside a classroom and nowhere to escape, a television monitor broadcasts a terrified Hae-yeong, the top student at the high school, tied up and seated on a chair inside an aquarium that slowly begins to fill with water. A voice from the monitor announces if the 24 cannot finish the exam administered within the allotted time given, Hae-yeong will die and so will everyone held captive inside the classroom. Thus begins the examination that will determine whether they live or die.

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