The Beasts of Clawstone Castle by Eva Ibbotson
When Madlyn and her younger brother Rollo are sent to stay with their great-aunt and -uncle Clawstone at crumbling Clawstone Castle, they discover something wonderful, and something worrying. The wonderful: the herd of truly beautiful cows (yes, cows) that the family has been safeguarding for generations.The worrying: the Castle has no money, and brings in very few tourists. They’re all interested in the much fancier tourist site at the castle down the road. The solution: Madlyn and Rollo bring in a truly unique attraction–ghosts. Their plans succeed far beyond their wildest dreams, but this attracts the attention of their unscrupulous neighbours, who aren’t keen on the competition… Dastradly doings and fiendish plots ensue.
Amusing and clever, with all the pieces falling together nicely at the end, but not quite the complex machinery of Star of Kazan or even Dial-a-Ghost. The protagonists are kind and clever and the villains are nicely despicable. Ibbotson’s characters still stand out as individuals and are quirky without being overbearing, and really, with the sort of stories she spins, the plot’s the thing.