Milly and Tilly are googly-eyed cats who belong to a cheeky little baby called Penny. During the day, they sit on her mat playing games and acting like normal toys. During the night when Penny is asleep, they creep out the back door in search of fun and adventure, ransacking bins, scrapping with other cats and generally causing mischief. At the end of the night, they sneak back inside and wipe their paws clean so Penny doesn't know that they've been out all night. However, one day in winter, heavy snows falls. The cats decide to be brave and sneak out. But the snow is too deep for their little paws and they get stuck. What will they do? How will they escape?