A military aircraft crashes in central London, releasing its highly classified contents. Following the crash, a malfunction at the Storage 24 facility causes the security shutters to lock, trapping several people inside: Charlie, his best friend Mark, Charlie's ex-girlfriend Shelley, her best friend Nikki, Nikki's boyfriend Chris, the building receptionist, Jake and a maintenance engineer, Bob. Charlie arrives at the facility with Mark shortly after the incident. However, since the facility’s power is intermittently failing and everyone else is forced back together when they realise they cannot leave the building.