Andy and Terry live in a 13-storey treehouse. They’ve also got a new book to write, but there’s a problem. A BIG problem. Well, quite a few big problems actually… On a hill not too far away there is a tree. And in that tree there is a tree house. And in that tree house there is a bowling alley, a see-through swimming pool, a tank full of sharks, a giant rope swing, a library full of comics, a secret underground laboratory, a vegetable vaporiser and a free marshmallow-dispensing machine that follows you around and automatically shoots marshmallows into your mouth whenever you are hungry.