Ce livre est en fait la suite du Château des Nuages, voici le résumé en anglais, puisqu'il n'est pas encore sorti en France :
Charmain Baker has led a respectable, sheltered life. She has spent her days with her nose in a book, never learning how to do even the smallest household chores. When she suddenly ends up looking after the tiny cottage of her ill Great Uncle William she seems happy for the adventure, but the easy task of house-sitting is complicated by the fact that Great-Uncle William is also the Royal Wizard Norland and his magical house bends space and time.
Though she is supposed to clean up the mess Great-Uncle William has left the house in, Charmain knows next to nothing about magic, and yet she seems to work it in the most unexpected way. The house's single door can lead to almost any place - from other rooms like the kitchen, to faraway places, and even other time periods. In her first days in the magical house, she ends up looking after a magical stray dog named Waif, had an encounter with a horrible lubbock, a confused young apprentice wizard named Peter shows up, a box of the King's most treasured documents, and a clan of small blue creatures called Kobolds.
When Charmain is caught up in an intense royal search to remedy the kingdom's troubles, she encounters Sophie Pendragon, her son Morgan, a beautiful child named Twinkle (who is really Howl in disguise), and their fire demon Calcifer.
She is soon involved in curing the kingdom of its ills and restoring the long-lost Elfgift.