Weeks after her disappearance, Liz Dunn (Thora Birch) stumbles back to her school and screams for help. Dr. Philippa Horwood (Embeth Davidtz), a police psychologist, is assigned to question Liz and determine what happened during her disappearance. In order to escape a class field trip, three rich teens are given a proposition by the school nerd, Martyn (Daniel Brocklebank). In exchange for some money and allowing his best friend Liz to come along, Martyn will hide them in an old underground war bunker. When the class trip is over, Martyn will come unlock the door to the hole and let them out. This offer is too good for the Mike (Desmond Harrington), Frankie (Keira Knightley), and Geoff (Laurence Fox) to pass up. So the three of them and Liz enter the hole prepared for a good time of partying. However, after the week is over, Martyn never returns to open the hole's door. The four teens remain trapped inside the hole as water and food run out. But somehow, Liz survives.