10-year-old Tully is a servant at the beautiful Mollet estate. She spends all day washing, polishing and polishing a huge house to a shine, but for now no one sees - she learns to read! Tully has a true friend - a squirrel named Tail. Together they have more fun, and they unravel the oddities happening in the estate!Lady Beatrice Mollet is sure that ghosts have wound up in the estate - and asks the medium Madame Wormwood for help. But Tully does not believe in ghosts, because even in the Secret Library, where there were many books about the secrets of the world, she did not find information about them. Yes, and Madame Wormwood does not inspire confidence at all ... But then who then rumbles at night and scares the inhabitants of the estate ?! It's time for Tully to investigate!