Olive is an only child. She lives by the sea in a ramshackle old house with her mother, Mog, successful, busy and hardly ever at home. Olive is very pale and very quiet and she doesn't quite fit in. But she has a best friend, Mathilda, and that's what matters.

And then Mathilda decides to be someone else's best friend.

Just as life really can't get much worse, Pip shows up. Brash, loud Pip, who is everything that Olive is not, and is about to cause Olive a whole heap of trouble - and open her up to a whole new world of possibilities.