When Liz Dunn and three of her prep school friends decide to bail on their scheduled weekend field trip and hide in a long-abandoned bomb shelter, they expect to party and hang out. They don't expect someone to lock them in. As anxious hours turn into desperate days, fear and insecurity erupt uncontrollably as their spontaneous adventure turns into a bloody fight for survival.
|Embeth Davidtz||Dr. Philippa Horwood|
|Steven Waddington||DCS Tom Howard|
|Emma Griffiths Malin||Daisy|
|Jemma Powell||Minnie (as Gemma Powell)|
|Gemma Craven||Mrs. Dunn|
|Kelly Hunter||DI Chapman|
|Kevin Trainor||Boy in School|