When eleven-year-old Edie Winter finds a mysterious box on the London Underground she's amazed to discover that it's home to a family of Flits - tiny winged people. But Impy, Speckle and Nid need Edie's help. Not only do they need supplies (rice crispies, sugar sprinkles, digestive biscuits and raisins) and someone to look after them, but their brother Jot has run away and they need Edie's help to find him.