And now, Katy, it's your turn. Tell us what you're going to be when you grow up.' 'I'm not sure about what I'll be,' replied Katy; 'beautiful, of course, and good if I can. That's what I'd like to be. But now I'll tell you what I mean to do...' Tomboyish Katy Carr is tall, gangling and full of mischief. Constantly scheming and playing with her brothers and sisters, 12-year-old Katy dreams that one day she will be 'beautiful and beloved, and amiable as an angel'. But goodness and obedience don't come easily to Katy, who has promised to be a good stand-in mother to her younger siblings but finds it difficult to stick to her word. When her bedridden cousin Helen comes to stay, Katy becomes enchanted with her as the living embodiment of goodness and light.