Corinna Stonewall is fifteen years old and an orphan. She is also Rhysbridge Foundling Home's Folk Keeper - a difficult and dangerous job which consists of looking after and controlling ‘the Folk' - spiteful, maverick, savage creatures who live in the cellar and will only be prevented from spoiling the milk, terrifying the livestock and other disruptions by gifts of cream, salt pork and similar luxuries. But there are many questions about Corinna. Who are her parents? Why does her hair grow two inches a night? Why is she always drawn to the sea and long for the sweet taste of fish?