Andy and Terry's incredible, ever-expanding treehouse has 13 new storeys, including a watermelon-smashing level, a wave machine, a life-size snakes and ladders game (with real ladders and real snakes), a rocket-powered carrot-launcher, a Ninja Snail Training Academy and a high-tech detective agency with all the latest high-tech detective technology, which is lucky because they have a BIG mystery to solve - where is Mr Big Nose???