A group of youngsters encounter a mysterious bad-tempered creature with the power to grant wishes.
Anthea thinks of a wish: but doesn't consider what effect it might have on the baby.
The youngsters' latest wish transforms the house into a castle : but fortunately Martha fails to notice.
The children learn an uncomfortable lesson about the implications of making rash wishes.
The relieved children think they've finally got the better of the mischievous sand fairy; but have they?
The sand fairy disappears, leaving the children to clear up an appalling mess before their mother gets home.