When Madlyn and her younger brother Rollo arrive at crumbling Clawstone Castle, they can see that emergency action is needed before Clawstone falls down completely. With the help of a team of homeless, scary ghosts - including a one-eyed skeleton and Brenda the Bloodstained Bride - they hatch a spooky plan to get the money rolling in. But with a sinister scientist on the loose, money might not be enough to save the mysterious beasts of Clawstone Castle . . .