A fun, fast-paced, school-based mystery for 8-11 year olds. When William Crumble injures his arm on the school football field, an X-ray reveals a small key hidden in his wrist. The key has opened a vault beneath his school, releasing every pupil's anxieties and embarrassing moments. Somehow, William has been chosen to fix it - even though he's scared of getting things wrong. A funny and mysterious tale about school, friendships and overcoming fears.