"Look," says the woman, holding out a shoebox with two holes at one end. So you do - and find two eyes looking back at you. Some three hours later, you realise this was, at a glance, what Portuguese artist Patricia Portela's refreshingly ambitious, astutely engineered trilogy would have you ponder - the relationship between watcher and watched that says: "If you can be seen, you exist".

The pivotal figure in the piece is Flatman, played with roguish panache by Anton Skrzypiciel. Part one introduces us to his world, the two-dimensional Flatland: projected on to a huge "book", it is a multimedia realm of documented fact and fiction that Flatman can inhabit but never experience. He wants to live it large in a 3D world - ours - and he has a plan. As long as we keep him in our sights, he is "for real". Cue a blacked-out bus ride to a deserted warehouse where there's a pell-mell slippage between audience as spectators and audience as hostages.

Skrzypiciel, in James Bond tuxedo and Dorothy's glittery red shoes, keeps switching from the terrorist who needs visibility - so he threatens brutality - to the cabaret illusionist who cuts people up for our entertainment. We're released, but brought back. Fed pizza and cocktails. Shown alarming footage that might be fact or fantasy while our own experiences - including escape down a bouncy chute - are filmed, to become part of the final "recovery" section back at the Tramway. A monolith of monitors beams out the news, with our kidnapping the springboard for a stream of "reality" that we know, for a fact, was brilliantly contrived play-acting with Skrzypiciel the puppet-master par excellence.