Rosalind and Robbie don't want to spend the summer stuck in their dad's new house with irritating Smash and her glamorous mum. Dad's biggest wish is for everyone to get along. So when he suggests a picnic in nearby Oxshott woods, the children grudgingly agree. That afternoon, in a golden sandpit, Rosalind makes a wish of her own and something extraordinary happens. It just might change their summer from weeks of rows and bickering into the best holiday these four children have ever had.