Like Nesbit's Railway Children, the story begins when a group of children move from London to the countryside of Kent. While playing in a gravel pit, the five children--Robert, Anthea, Cyril, Jane, and their baby brother, the Lamb--uncover a rather grumpy, ugly and occasionally malevolent sand-fairy known as the Psammead, who has the ability to grant wishes. However, the Psammead has been buried for so long, he is no longer able to grant individual wishes. Instead, he persuades the children to take one wish per day, to share amongst the lot of them, with the caveat that the wishes will turn to stone at sundown. This, apparently, used to be the rule in the Stone Age, when all children wished for was food, the bones of which would then become fossils. However, when the children's first wish--to be "as beautiful as the day"--ends at sundown, it simply vanishes, leading the Psammead to observe that some wishes are too fanciful to be changed to stone.