Teen fiction. In great condition besides minor damage to the edges of the dust jacket.
 
"Bookworm Rosalind and her younger brother Robbie are on a summer holiday cooped up with their irritating stepsister, Smash, and their adorable little half-sister, Maudie. Things change when the bickering group takes a trip to a nearby golden sandpit in the woods. There, they unearth a strange, grumpy, ancient sand-fairy known as the Psammead.
The Psammead has the power to grant each of them one magical wish a day. However, the children quickly learn that getting exactly what you wish for comes with complications, and their daily wishes often go hilariously wrong before the day ends."