Night falls and Cat Country comes to life: town walls turn into roads, roof and treetop become mountain and field. The black cat Carbonel and his consort, Queen Blandamour, have long reigned over this magical place, where humans are scarce, cats roam freely, and the rivers flow with cream. But the wicked Grisana, a beautiful gray Persian who makes Lady Macbeth look like a lap cat, has plans of her own for Cat Country, and Carbonel and his children, Prince Calidor and Princess Pergamond, are all that stand between her and the throne. With the backing of Carbonel's old foe, the witch Mrs. Cantrip, and her apprentice, Miss Dibdin, Grisana may be unstoppable.

Luckily, Carbonel can count on Rosemary and John, his young friends from Carbonel: The King of the Cats, to come to his aid. Together with the good creatures of Cat Country-and with the help of a few magical spells-the children confront Grisana and her nasty crew. It is a battle for the future of Cat Country and only the strongest magic will prevail.