Plot summary

Liz Dunn (Thora Birch) returns to her rural English boarding school bloodied and in shock. The police are called immediately for Liz has been missing from school and home for 18 days. Later, and still in shock, Liz Dunn tells her story to the psychiatrist appointed by the court, Dr. Philippa Horwood (Embeth Davidtz). The plan was that she and three more students would hide inside a war-time bunker because they wanted to avoid a school excursion to Wales. They did not want to spend the holidays with their families either. The three other runaways are popular and successful but Liz is the school outcast. She was hoping that the time in the vault with Mike Steel (Desmond Harrington) would make him forget his girlfriend, the popular Frances 'Frankie' Almond Smith (Keira Knightley) who also tags along. Geoff Bingham (Laurene Fox), Mike's best friend, was also in the bunker. The excursion people would think they were at home on holidays, and the students' parents would think they were in Wales. Nerdy Martyn Taylor (Daniel Brocklebank), supposedly Liz's only friend, was supposed to lock the gate/exit to the bunker, go home to his family and, when he returned three days later, he would unlock the door and they will all go back to school. However, at the end of the three days, Martyn never showed up to let them out. At this point, at the police station, Liz breaks down because she is too traumatized by what happened next at the bunker to continue talking with Horwood.The interviews resume a few days later. Liz's mother Mrs. Dunn (Gemma Craven) doesn't think it's necessary to go on with the questioning but Dr. Horwood insists. Felling better, Liz tells the story of what happened when they realized Martyn wasn't coming to unlock the door. Liz says that it he's doing this to get back at her because Martyn is jealous that she is in love with Mike. The four friends tried to smash the door, find another exit, all to no avail. They decide they will have to wait until Martyn takes pity on them.However, in spite of rationing, they are running out of food and water. On day 10 in the hold, once they run out of food, hunger and thirst cause Frankie to have a heart attack and she dies in a disgusting toilet booth swarmed by flies. The three remaining students cannot do anything else apart from talking among themselves, arguing and making up stories to spend their time. They get so weak that they can barely move. Suddenly, a soft pop and a hiss is heard. Geoff has hidden a last can of Coke from the others. Mike gets so angry at his selfishness, he attacks Geoff and kills him by banging his head onto the floor several times.The questioning gets interrupted once and again. This time by DCS Tom Howard (Steven Waddington) who thinks that Phillipa's conversations with Liz are just a waste of time. Tom has been questioning Martyn, who wants to talk with Liz face-to-face. In private and away from the police station, Martyn asks Liz why she's doing this because now the police suspect him of murder. Liz kills Martyn and pushes him down to the river. Back at the police station, Dr. Horwood, who now suspects that Liz is not telling the truth, questions her some more.Liz begins her story again; Now that it's only Liz and Mark in the hole. Mark starts to show some tenderness towards Liz. At that moment, Liz shows Mike the key to the door. She had had it the whole time. Mike is furious. Because of her actions, Frankie is dead and he killed his best friend. He screams at her and threatens to kill her but he falls down the metallic stairs and dies. Dr. Horwood stares at Liz in horror. She was always the "leader of the pack" at school, snobbish, stubborn and conceited, childish and obsessively in love with a boy who wouldn't give her the time of day. Her plan had been to make Mike notice her and realize he was in love with her. Dr. Horwood tells Liz that she has to tell the police what she's done.At that moment, Tom Howard walks in the room. Liz pretends to be afraid of Dr. Horwood. Tom tells the doctor to stop stalking Liz or she will lose her job. Horwood gets frantic, because she is the only person in the world who realises what has truly happened: Liz caused the death of four people in order to have the boy she was going after. But having failed that, Liz returns to her perfect, wealthy life, knowing that she got away with everything while Dr. Horwood looks on with silent anger and defeat.