In search of the perfect holly with shiny berries to decorate his Christmas tree Little Mouse begins to make his way home. Suddenly soft white flakes begin falling all around him. "The sky is coming undone!" fears Little Mouse. As he hurries home to tell Big Mouse his imagination overwhelms him. First he sees a "strange creature" waving its arms at him as he passes the water. Then when he turns around he sees that an invisible monster is leaving footprints right behind him! Finally, after running in circles Little Mouse arrives home only to find a giant white monster in front of the door. When Big Mouse finds Little Mouse outside he reassures him that the sky is not coming undone, but that it is snowing; after explaining away Little Mouse's fears, he shows Little Mouse that snow makes for a magical Christmas indeed.