Kneebone Boy by Ellen Potter
The only thing KNEEBONE BOY has in common with Ellen Potter's other books is that it is excellent. Told by one (you don't know which) of three odd semi-orphans, the book follows the trio on a search for their missing mother, in a house strange enough to be magical. Only it isn't. The characters are at once bizarre, and human, and the end is an absolute surprise. Amazing!