Hollow Fields and the Perfect Cog (Hollow Fields) (Book:4)

With the menace of Miss Weaver's reign of terror supposedly behind them, the students of Hollow Fields can look forward to a more peaceful curriculum run by her ethically-minded successor, Principal Bleak. But there's one problem-rebuilding the school after Miss Weaver's reign has left Hollow Fields broke! If the school can't scrape together the cash to pay its staff or maintain its grounds, the Board of Unprincipled Mad Science Education will have it shut down and use the student body for scientific experiments. Not wanting to be separated from her new friends, Lucy stumbles upon a chance for Principal Bleak to save Hollow Fields. All they have to do is win the inter-school mad science competition and along with it, a hefty cash prize. But just what kind of things go on at a mad science fair?!