Giant Productions is a Glasgow company that specialises in making theatre for children with special needs and its latest show, The Puzzle, took as its premise that these children live over-protected lives and need to learn how to play.
Accordingly, deviser and director Katrina Caldwell made her stage and auditorium from brightly coloured soft play mats and shapes - everyone had to remove their shoes before going in - and simply turned her two performers loose.
They cast themselves as young girls: Bec Phipps was gauche but willing to try anything and Laura Cameron Lewis was her really clever friend who could do things such as dive into a wheel and then roll herself around the stage.
At first they experimented cautiously with the shapes, throwing themselves on, over and through the cubes, triangles and circles, but then the play became more inventive.
With the help of a carefully insinuated soundtrack and projected designs, they used the shapes for a series of improvised scenarios that took them across the sea in a steamship, on underwater safaris in air bubbles, back in time to the age of the dinosaurs and finally on a ride in a space rocket to other worlds in search of alien life. At the same time, the pair cleverly sketched in some principles of play: that you must play by the rules, you cannot be captain every time and you need to say sorry when you are in the wrong.
The actors were so skilful at showing the pleasure of improvised play that after 10 minutes I was more than ready to join them, an impulse that must have been shared by the rest of the audience. After all, we had already taken our shoes off.
But the pleasure was denied and instead this indefatigable pair delighted us for an hour, bouncing with energy, bubbling with humour and creativity, creating animals out of their bodies and improvising little dramas into which the children readily projected themselves.
They were unsparing. The pair even broached the geology of oil exploration, telling us about the comet that destroyed the dinosaurs and using the shapes to demonstrate sedimentary dating.
This was a cross-current and a reminder that Giant is a company with a set of strong and unique principles, which can sometimes seem to be attached to its work as afterthoughts rather than as informing ideas.
Though the performance teeters dangerously close to one of the cardinal sins of theatre - the cast should never seem to be having a better time than the audience - the sheer vitality and talent of the two actors, both skilled in movement and clown technique, won the day.
Giant Productions, tel 0141 334 2000www.giantproductions.org The Puzzle tour to theatres and schools finished this week