It’s work experience week for Lucy Gardner and her classmates, but Lucy isn’t happy – she has to work in an old bookshop that nobody ever goes into. And worse, the owner of the shop is a very grumpy lady. But when Lucy finds an old diary in the shop one day, things start to get interesting. Many years ago, the person who wrote the diary hid something very valuable. But what was it, and where is it hidden? It’s a mystery – a mystery Lucy is determined to solve.