Molly Carver, aged 7, has just moved to France. Whilst helping her mother clean the kitchen in their new home she discovers a shoebox underneath one of the cupboards. Inside the shoebox there are nine little beds, each cover embroidered with beautiful initials. The covers have been thrown back as if the occupants have left in a hurry. Against her mother's wishes Molly leaves the box at the back of the cupboard. That evening Molly loses a tooth and leaves it under her pillow. The next morning the tooth has been replaced by the tiniest of envelopes. With the help of her new best friend Eloise, Molly reads the letter and discovers that it has been written by a little mouse: it is a mouse, not a tooth fairy that takes away your teeth in France. Molly's tooth-mouse is called Myrtille (Mer-tee which means Bilberry). Myrtille thanks Molly for her tooth and for not throwing away her family's home. Molly and Myrtille begin to write to each other and Molly finds out about Myrtille's family and the woodland creatures' Autumn Ball. Molly is desperate to see it the Autumn Ball but doesn't dare ask. Eloise comes to stay the night and tells Molly her elderly neighbour, Madame Bouton, is a witch and they should stay up to watch her on her broomstick. But, Eloise falls asleep and Molly looking out of her window sees instead the mice picnicking in the moonlight. When Eloise's mother becomes ill, the mice make medicines to help her get better, but, when Molly's teacher is replaced by a horrible teacher (The Witch) it is Madame Bouton who provides a plant remedy that will help Molly get her old teacher back. As for the Autumn Ball...well that would be telling