Katie and Harry are twins who wish it was their birthday every time a party invitation comes. Despite their disappointment, they have a megasauric time at Tim’s dinosaur party, a wonderfully wild time at Nicola’s picnic in the park and an excitingly scary time at George’s Halloween party. But when their birthday finally arrives, although their party isn’t a dinosaur party, a picnic in the park, or a Halloween party, for Katie and Harry it is quite the best party of them all!