Part of the strategy there is often to let the nuts and bolts of playing the instruments involved become part of the material of the piece. The medium is, in the famous McLuhanism, the message. So on one level Tempestade is about the craft of using puppets as much as about telling a story. Which is quite spooky when you consider that Prospero is often referred to as a puppetmaster.

The performers are mostly behind a white curtain using their own bodies and glass figures to throw shadows, but on the side wall of the tiny Richardson Hall in Wordsley we see other shadows from which we can deduce the mechanics of what is actually going on to produce the effects on the screen.

If I wanted to be a candidate for a Pseud's Corner listing, I could call it a Platonic subtext on what the audience is supposed to be seeing. But I won't, I'll just say it's like the conjuror telling us how he produces the rabbit out of the hat, but making that revelation part of the act - anyone who has seen the Pixar cartoon before the current cinema hit Wall-E will know where that can lead.

Co-director Clive Chandler called it 'a bit of fun', but he's a showman, and perhaps a bit shy about owning up to the depth of intelligence on display in this fascinating piece.

There's water and sand - elements of the magical industrial process of making glass. The storm sequence has swirling shapes which reminded me of old monochrome films of glass blowing being shown in various places throughout the festival. There are real time video projections, a Caliban made from a sea sponge, Ariel looking like a glass Gingerbread Man dissolving into flashes of white heat and scarlet swooshes which any marketing department would pay a big fee for.

Shadow sequences play on the reflective and refractive qualities of water and other endlessly fascinating elements. The white-robed performers coming front of screen, the glass figures referencing traditional puppet heads with their nose shapes and, the wonderfully evocative music by Ed Briggs. The score is realised largely on glass instruments plus electric and acoustic guitars and ukulele plus a custom-built instrument the company is calling a double psaltery (above), which has a grid of strings producing ethereal harp noises and which is thrown in shadow on to the curtain by an overhead projector.

There are slides which echo the magic lantern shows which must have been seen in the hall in its early days - and which we see literally slide into place. There are bubbles, a galleon on a stick and a despairing little puppet left staring over the curtain at the disappearing backs of the performers as they leave the hall. Can Caliban/the puppet exist without the company?

Yes, all the elements aren't exactly integrated into a satisfying whole, and it's slow to get going, but technically it's a brilliant achievement, particularly as it's a very low-tech affair. The staging was borrowed from a local school, for instance.

The show is a collaboration between PuppetLink and the Portuguese SA Marionetas and there are tentative plans to tour the production. I would love to see how it develops. There are so many innovative and original elements in Tempestade, its sheer bravura imagination and pioneering techniques must surely lead on to other ventures.