Cavernstone Grey is the main setting of The Owl Keeper. Maxwell Unger, along with many other people, live there. Rose and her father run from place to place around Caverstone Grey, and the High Echelon is based there. In Cavernstone Grey, hot chocolate and truffles are the main product. These contain traces of Deadly Purple Sphinx, a highly poisonous plant, to produce mind control bit by bit. This idea is part of the High Echelon's evil bidding. Caverstone Hall is where Max's parents work, and they always come home late and exhausted. Caverstone Grey is said to have "The world's finest chocolate." But when Max and Rose set out to look around, Max discovers that Caverstone Grey and Caverstone Hall have many secrets to be uncovered, and that the High Echelon smuggles plants like Deadly Nightshade and Deadly Purple Sphinx and turns them into poison, putting them in different colored boxes of chocolate-containing foods and beverages, like hot cocoa. The Dark Brigade patrols this place, sending in anyone out at night. They inject plagues that spread from the Great Destruction into the remaining wolves, thought to be extinct, and the Dark Brigadiers use them as gaurd dogs, starving them so much that they attack on sight, killing anything in seconds. Mostly all of the businesses in Caverstone Grey were seized by the High Echelon and shut down.