Arthur, the sixth trustee Saturday and another powerful House creature called the Piper all receive a message from lady Friday that she has abdicated the rule of her part of the House, called the 'Middle House', and that the first of them to reach her scriptorium can claim the fifth Key and her domain as their own. Along with each message is sent a 'transfer plate' that sends whoever touches it straight to the Middle House (which is a giant, terraced mountain). Arthur accidentally uses the plate.