Charlie's Uncle Paton has dashed off to try to stop the Yewbeam aunts' latest plan, but when Grandma Bone greets the arrival of Belle with delight, could this be what Paton left hoping to prevent? At Bloor's, Emma finds art teacher Mr Boldova is the brother of the mysterious Ollie Sparks, made invisible by the blue boa. Belle joins the more nastily endowed, and Charlie realises she is Yolanda, an evil shapeshifter who brought up Charlie's nasty aunts. She wipes Mr Boldova's mind, leaving only his rat, Rembrandt, to tell Billy Raven what's happened. Soon Charlie will have to face the terrible sorcerer Skarpo again to free his friend. When Julia Ingeldew is threatened, Paton furiously springs into action.