▁for ▁I - na . ▁After ▁several ▁strange ▁inc idents , ▁the ▁class ▁is ▁interrupted ▁by ▁a ▁TV ▁showing ▁of ▁the ▁top - ran king ▁student , ▁Min ▁H ye - ye ong , ▁being ▁tra pped ▁in ▁a ▁glass ▁being ▁slowly ▁filled ▁with ▁water . ▁A ▁voice ▁over ▁the ▁PA ▁system ▁announ ces ▁that ▁questions ▁will ▁be ▁pos ed ▁to ▁the ▁class ; ▁failure ▁to ▁answer ▁them ▁in ▁time ▁will ▁lead ▁to ▁their ▁death . ▁It ▁also ▁war ns ▁them ▁and ▁their ▁two ▁teachers , ▁H w ang ▁Ch ang - wo ok ▁and ▁Ch oi ▁So - ye ong , ▁against ▁leaving ▁the ▁school . ▁The ▁class ▁fails ▁to ▁solve ▁the ▁first ▁question ▁to ▁save ▁H ye - ye ong . ▁ ▁Despite ▁the ▁warning , ▁the ▁class ▁tries ▁to ▁leave , ▁only ▁to ▁find ▁that ▁a ▁teacher ▁and ▁hall ▁monitor , ▁Mr . ▁Lee , ▁was ▁be aten ▁to ▁death , ▁leaving ▁only ▁Mr . ▁Kim ▁to ▁guard ▁them . ▁The ▁students ▁split ▁up ▁and ▁try ▁to ▁answer ▁the ▁questions ▁while ▁also ▁attempting ▁to ▁find ▁a ▁way ▁out . ▁Several ▁students ▁die , ▁then ▁Be om , ▁who ▁earlier ▁tries ▁to ▁str angle ▁I - na ▁and ▁was ▁put ▁in ▁a ▁mental ▁facility , ▁esc apes ▁and ▁attempts ▁to ▁kill ▁I - na , ▁but ▁Hy un ▁shield s ▁her ▁from ▁the ▁attack ▁and ▁dies . ▁Ch ang - wo ok ▁then ▁k ills ▁Be om . ▁I - na ▁disco vers ▁to ▁her ▁horror ▁that ▁My ong - he