The police consider it a tragic accident that Yuko Moriguchi's four-year-old daughter drowned in the school swimming pool. But Yuko, a teacher at the school, knows that two of her students are responsible for Manami's death — and she has no intention of letting the killers walk away unpunished. On the last day before the holidays, she tells her class that she has one final lesson to teach them… But her deviously conceived plan for revenge spirals out of her control, setting a deadly drama in mot...
