Monica Plum's Horrid Problem. A Story for Children of Troubled Parents, Paperback

Monica has a horrid problem. It gets everywhere: into her schoolwork, her dreams, and her ability to make friends. People keep telling her to cheer up. She feels as if she is carrying around some very heavy luggage. Then one day, a helpful teacher sees how miserable Monica is, and tells her about the knights in the world, who are posing as people.