Rule No.1: Avoid Trouble (Paperback)

Clara's highly cherished rule, Avoid Trouble, is in jeopardy. Her trouble Spiderman-like sense is going crazy.
It's not Reggie - He's happy and chatty. It's Bella - She's overheard a plan to 'shake the class up', and is now dragging Clara along on her mission to stop the school bullies from ruining the afternoon's science lesson. This all sounds like serious trouble. No good has ever come from getting into trouble - or has it?
Join Clara as a mysterious grey smoke shrinks her, she gets mistaken for a mouse, nearly trodden on, knocked over by a stray football and enters a hamster's cage on a rescue mission.