Mirabelle's mum is a witch, her dad is a fairy, and she is a bit of both!Mirabelle doesn't mean to cause trouble, it just seems to follow her round. But when she and her brother go to stay at their fairy grandparents she is determined that nothing will go wrong, and she is going to be on her very best, most fairy-like, behaviour. But being good all the time is really tiring.

And a little bit of mess leads to a little bit of secret witch magic, which leads to even more mess, and even more magic, until everything is in total chaos! Can Mirabelle get the mayhem under control before Granny finds out?