Anna and Holly have spotted an advert in the paper for a Holy Moly Holiday - the intergalactic vacation of a lifetime. But how will they get enough money? Simple: they'll become royal babysitters for a day. Unfortunately, the girls are in for a shock. Once King Steve and Queen Sheila have left, they discover there isn't just one prince to look after. There are six. And worse, the country's arch enemy, King Alaspooryorick of Daneland, has decided to stage an invasion.