Charlie and his sister Georgie Oughtt have been sent to visit their grandmother Pearl, and this troubles Charlie for three reasons. The first is that he's an exceptionally nervous twelve-year-old boy, and he worries about everything. The second is that the other children in his neighborhood who pay visits to their grandmothers never return. And the third is that Charlie and Georgie don't HAVE any grandmothers. Upon their arrival, all of Charlie's concerns are confirmed as "Grandmother Pearl" quickly reveals herself to be something much more gruesome than even Charlie's most outlandish fears could have predicted. He and Georgie are thrust into a creepy underworld created from stolen nightmares, where monsters disguised as grandmothers serve an ancient, evil queen by holding children captive as they slowly drain each one of their memories and dreams. But something is different about Charlie. His worrisome nature, so often a burden, gives him an edge in this frightening world. Will he be able to harness this newfound power to defeat the queen and save his sister?