It is Christmas Eve, and Big Mouse and Little Mouse are decorating the tree. Little Mouse scampers out to search for holly, but finds big white flakes falling from the sky. "Goodness me!" he cries. "The sky is coming undone!" And as Little Mouse's world is covered in snow, de discovers strange things all around him. . . .
There's a Mouse Ness Monster making faces at him, an Invisible Monster whose paw printss follow Little Mouse wherever he goes, and a huge White Mouse waiting for him at home!
But Big Mouse is waiting for hime, too, and he shows Little Mouse that snow isn't scary at all. In fact, it's magical. And that a very snowy Christmas is a very good Christmas indeed!