Millie is different to everyone else. She has rain in her brain and butterflies in her tummy. Her friends, family and teachers always try to make her feel better, but the only thing that works is socks. Stripey, spotty, odd, long, short, holey, funny - each morning before school Millie carefully chooses the socks that make her feel the best. But when she loses her favourite pair to the washing machine, Millie discovers that her superpowers weren't on her feet, but inside her all along.