When five siblings Cyril, Anthea, Robert, Jane and their baby brother, the Lamb discover a sand-fairy in their gravel pit, they are jolly surprised and a little delighted. Even better, the Psammead is able to grant them wishes, although the magic wears off at the day's end. Unfortunately, all of the wishes the children make go hilariously wrong and they soon learn that their foolish desires are more likely to get them into trouble than get them what they want!