Almost every Sunday a little girl named Iris visits her grandfather, Wally Walters. He's a keen cake maker and always bakes a cake which they sit and share. Noticing that the next Sunday will be Iris's eighth birthday he sets about making a cake, but this will be no ordinary cake. Wally Walters has a magic rhyme he sings as he mixes the cake, the ingredients becoming more and more fantastic... and thus the Magic Birthday Cake is created; a very special birthday surprise!