Keeper of Magic

Keeper of Magic by Linda Chapman. paperback edition. ISBN: 9780141321226.

Laurens twelve-year-old cousin Hannah is coming to stay. Hannah is pony mad and Lauren cant wait to introduce her to Twilight. But when she arrives, Lauren is disappointed to discover that Hannahs not into ponies any more and prefers doing other things. Old Mrs Fontana, the only person who knows that Twilight is really a secret unicorn, explains to Lauren that time cannot stand still, and that people change and life moves on. She gives Lauren a small chest with a key and asks her not to open it until the time is right. Lauren is curious but has a worried feeling that there is more to Mrs Fontanas words than she is letting on...