Four school friends escape the tedium of a field trip by hiding in an underground bunker, only to realise they are inexplicably sealed in. As panic gnaws away at them, tensions inevitably rise, and they desperately try to work out how they can escape. Thriller, starring Thora Birch, Keira Knightley, Desmond Harrington, Daniel Brocklebank, Embeth Davidtz and Steven Waddington