Ten-year-old Callie is desperately homesick. She misses everything about living in London--the apartment building where everyone has known her since she was a baby, her best friend, all the places that remind her of her mother, who died three years ago. She doesn't care to get to know Northern Ireland, no matter how friendly her next-door neighbor Sam is. Then a magical house crash-lands upside down in Callie's backyard, and its magician, Winnifred, turns to Callie for help. The Wanderdust that powers the house and keeps it (and Winnifred) healthy has flown away, leaving Winnifred at the mercy of malicious fairies and dangerous giants. She can't leave her house, so it's up to an eager Sam and a reluctant Callie to find the missing Wanderdust and bring it home again. And maybe, along the way, figure out what home means to Callie.