When Madlyn and Rollo are sent to staying at ancient Clawstone Castle, they soon fall in love with the house and its eccentric, penniless inhabitants. There's grumpy, limping Uncle George, mousey Miss Emily, and reclusive Cousin Howard who hardly ever leaves his library. But, the children are especially enchanted by the Cattle of Clawstone Park - rare and beautiful beasts, as white as snow and as wild as wolves. No one knows where they came from, but the owners of Clawstone have always protected them. So, as the castle crumbles away, Madlyn and Rollo devise a money-raising scheme. With the help of a gang of ghosts - including The Bloodstained Bride, an aristocrat whose heart is constantly being gnawed by a rat, Mr Smith the one-eyed skeleton, and a pair of dancing phantom feet - they turn Clawstone into a genuine haunted house! But, as the money rolls in, a ruthless plotter is close to carrying out his sinister ambition, a plan that could threaten the very existence of the fabled Beasts of Clawstone Castle...