Tree-mendous fun in 13-storey fantasy

Andy and Terry are two lucky guys who live in the most tremendous treehouse. It has a bowling alley, vines to swing on and when in need of refreshment they can head to the lemonade fountain and marshmallow-shooting machine.

It has a see-through swimming pool, which must not be confused with the shark tank. We can't see all of this on stage - we have to use our imagination.

This stage play, a close adaptation of the popular book, is a story of friendship, fantasy and procrastination amid the leafy green craziness of the Treehouse, now an institution among the under-12 set.

Andy Griffiths and illustrator Terry Denton produced the first of the Treehouse books in 2011 but had collaborated on many earlier books. Their history of studied silliness shines through, to the joy of young fans filling the theatre.

The storyline in the book follows our hapless team as they struggle to come up with a finished book for publisher Mr Big Nose. But instead of writing, they get distracted with mishaps and mythical creatures.

In Richard Tulloch's adapted stage version, Andy and Terry, played by Andrew Johnston and Matthew Lilley, are again in a tizz but this time their panic focuses on a missing script. The audience is here and the two main characters are present and correct. But where is the story?

The friendship of the characters Andy and Terry on both page and stage is warm and at the same time infuriating and puerile.

Infuriating and puerile give us conflict and humour, and that's as good a place as any to start a play.

Producer Big Nose and fearsome stage manager Val (Eliza Logan) fuel the lads' panic and push along the story of the missing story. Val softens, steps in to help and all three have a blast in the process.

It is this fascination with process - exposing the fourth theatre wall and the dread of the blank page - that makes the Treehouse constructive.

Or you can sit back and cheer its chaotic energy and fart jokes.