The kind of book I would have loved as a kid' – Tom Fletcher, author of The Danger Gang

Andy and Terry have added thirteen new levels and built their biggest and most astonishing treehouse yet! It has everything they – and you – could wish for including: an electric pony stable, a NOISY level, a weather dome (where you can have whatever weather you want whenever you want it), and an 100% edible gingerbread house and a potato-powered translation transmitter that allows you to talk to everything everywhere all at the same time.

There's also a hall of funhouse mirrors, which is the perfect place to hide from Mr Bunkoff who is trying to catch Andy, Terry and Jill in order to send them to school. But Anti-Andy, Terrible Terry and Junkyard Jill, their trouble-making opposites, are trapped in one of the mirrors ― and they want out. (Oh, and Mr Big Nose wants them to write their book . . . RIGHT NOW.) Can our heroes escape school, defeat their doppelgängers AND meet their book deadline?