Sibyl is the apprentice hotel witch at the splendid Grand Mirror Hotel. She is busy each day, under the watchful eye of her grandmother, drawing useful spell patterns to keep the hotel guests happy, spells to shine shoes, spells to make the pastry chef's cakes rise, spells to remove dust and spells to return lost things like hats and gloves to their owners. But Sibyl dreams of other possibilities, possibilities like her mother returning from the Black Mountains, and like Grandma letting her draw spell patterns from the Book of Advanced and Dangerous Magic. When Grandma gets stuck in last Tuesday, somewhere on the hotel's thirteenth floor, Sibyl must perform all the magic herself. Just when a very mysterious and perplexing problem arises and a very important guest must be taken care of. With the help of her friend Ahmed, the lift attendant, an aloof cat called Alfonso and Dora the concierge, Sibyl must solve the mystery of the missing shadows and find the right spell pattern to get them back. Will she open the Book of Advanced and Dangerous Magic? And will it contain the answers she needs?