This is the fourth installment in the wildly imaginative Treehouse Series by Andy Griffiths.
 
The story follows the ever-expanding, absurdly adventurous treehouse — now up to 52 storeys — featuring ridiculous and hilarious attractions like:
A watermelon-smashing level
A wave machine
A life-size snakes-and-ladders game (with actual ladders and snakes!)
A rocket-powered carrot launcher
A Ninja Snail Training Academy
A high-tech detective agency
All this is in place as our heroes, Andy and Terry, try to solve a big mystery: Where has Mr. Big Nose gone?