The Twice Lived Summer of Bluebell Jones

Two summers. Two girls. Same summer. Same girl.
On her thirteenth birthday, Blue makes a desperate wish. To be transformed into a cool, confident teenager. Enter Red, appearing from nowhere like a wacky fairy godmother. She's only visible to Blue - in fact, she IS Blue, but a year older. With Red by her side to guide her, Blue can avoid all the gruesome embarrassments! But her future self causes a heap of crazy trouble - and there are dark secrets she's not telling...