Once upon a time in Paris, begins Shibboleth's surreal urban fairytale. It has been devised, literally, on the rooftops of that romantic, yet mysterious, city where the company members trained with Jacques Lecoq.

Square is inspired by the Jewish theatre period of Russian painter Marc Chagall, who peppered his work of that time with crazily vivid images of fiddlers, flying samovars, severed heads and flickering candles.

Chagall wrote that he often took refuge on his roof and found ongoing inspiration there for his creative inner life. And it is towards this heightened existence that John McIlduff's Him hesitantly climbs, having spent much of his adult life hiding under tables, in cupboards, in any restricted space into which he could squeeze himself.

This prolonged hide-and-seek existence has come to pass as normality for Him and his girlfriend, Her (Emily Mytton). But when, one day, the ritual game produces no positive sighting, his ascent becomes her nightmare.

Up on the slates, in the rarefied air above the smog, Him encounters a strange companion, the Birdman (Anthony Hampton). They strike up an odd, circular, Beckettian partnership.

But it is not a partnership of equals. For as Him involuntarily sprouts feathers, a beak and powerful wings, Birdman remains a city gent, dressed as a ridiculous waddling creature.

Down below is Her, struggling with her private hell until she finds the means to join Him in a tragic attempt at flight.

This is another tantalising piece of theatre from a company whose collective imagination is rarely still.