The kitchen, the bedroom, the foyer - hell, you may need to buy a copy for every room in your dwelling. You wouldn't want to be making dinner and have to run to the den to see knotted guts and rotting corpses, have to get out of bed and go downstairs to make Nathan's eyeless gaze the last thing you see before you drift off, or have to invite guests any further into your home than necessary before terrifying them.
