If you stay inside, you are protected

Three teenagers are confined to an isolated country estate that could very well be on another planet. The trio spend their days listening to endless homemade tapes that teach them a whole new vocabulary. Any word that comes from beyond their family abode is instantly assigned a new meaning. Hence 'the sea' refers to a large armchair and 'zombies' are little yellow flowers. Having invented a brother whom they claim to have ostracized for his disobedience, the uber-controlling parents terrorize their offspring into submission.