It is a Psammead (voiced by Eddie Izzard), an ancient, ugly and irritable sand fairy the children find one day in a gravel pit. It grants them a wish a day, lasting until sunset. But they soon learn it is very hard to think of really good wishes, and each one gets them into more and more trouble. Magic, the children find, can be as awkward as it is enticing. There's fun for all the family, featuring an all-star British cast including Kenneth Branagh and Zoe Wanamaker.