The underpants of chaos / Sam Copeland, Jenny Pearson ; illustrated by Robin Boyden and Katie Kear.

Something bad is happening at Little Strangehaven Primary. What are the peculiar Shivers that keep striking the school, bringing Strangeness in their wake - from uncontrollable ballroom dancing to an attack by military chickens? Spy-detective Agatha Topps is determined to find out. She's the only person who doesn't forget the Strangeness as soon as it's over. At least, until new boy Lenny Tuchus turns up and remembers too. Their spy-detectoring leads them to the Book of Chaos, an ancient text which has been hidden away in the Room of Forbidden and Dangerous Books. Can Agatha and Lenny fight off attacks from evil underpants and Transylvanian gargoyles to stop the Shivers before their town is sucked into oblivion? Because power lies in books - especially this one...

8+ years old.