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???