Rosie Staples is determined that this year she will win the lead in this year's school play, but she needs some very serious magic if she is to defeat Maddison Diamond. Maddison is the teachers' pet and she always gets the lead, while Rosie has to put up with short, funny roles. So Rosie, who loves tricks and magic, saves her money and buys The Sooner it Happens the Better Magical Wishing Stone from the magic shop. But she is much too impatient to listen to the instructions (which have a personality of their own), and when she makes her wish to act like Maddison Diamond, she does everything wrong. Her wish is taken literally, and when she wakes up next morning she feels strangely unlike herself … And when she gets to school everything becomes even weirder!