At night in the park, Maria sees it for the first time: the little white horse. But Moonacre Castle holds even more strange beings within its centuries-old walls. They all seem to have been expecting Maria and want to communicate something to her. Moonacre Castle, the ancestral home of the Merryweather family, is 600 years old, and the young Maria moves there with her governess, Miss Heliotrope, after the death of her parents. The white horse that she thinks she saw in the moonlit park could simply have been a moonbeam. But what about the other inhabitants of the castle: the house and kitchen gnome Marmaduke Scarlet, the giant cat Zachariah, his assistant, and the lion-like dog Wrolf?.