Compagnie XY, Roundhouse, London

Time was when the chance of the Arts Council having anything to do with the circus was roughly on a par with unassisted human flight.

On the evidence of a little show called Le Grand C, though, it seems the unlikeliest things can happen. Having decided that circus is the new black, the funding body has thrown its weight behind Circusfest, a month-long jamboree in the circular Victorian engine shed that is now the Roundhouse. And yes, you'll not only believe men and women can fly: you'll see them do it so often that it starts to seem, dare I say it, ordinary.

Where all circuses were once variety acts, Compagnie XY, based in Lille, is something of a Johnny One-Note. The 17-strong troupe of gymnasts and strongmen limit themselves to one basic stunt: erecting human towers and then dismantling them again.

The minimalism extends to the equipment, too, or rather, lack of it. There are no ropes or scaffolding to aid levitation, no trampoline to bounce off. People simply scramble up one another, as if they were a vertical rock face but without the crampons and safety harness. Bare toes are left to seek their grip, monkey-like, in the soft backs of knees, in waistbands, under shoulder blades; body-towers grow ever more perilous as they get taller, like dominos piled end to end with infinite care – two, then three, then four, the expression on the face at the bottom of the stack glazing over as the man (not always one of the bulky ones) steels himself. It all happens with stealth, as if any sudden noise or movement would send the whole thing crashing down, and I suppose it might.

The show's title, I hazard, refers to le grand chapiteau, or big top, and the circularity of the brick-built Roundhouse is in this respect ideal. Its cavernousness, though, threatens to swamp this intimate show, whose rejection of old-style glitz extends from the girls' demure cotton skirts to recorded accordion music so sparse that it peters out into lengthy silences. I was lucky enough to be sitting so close that I could have wedged my chin on the stage, and it was a treat to be able to discern the flickers of concern, as well as triumph, behind the acrobats' eyes. From further back, though, you'd miss that. And the determined untheatricality of this notably un-shouty spectacle might then have felt rather dour.

There are many memorable things, though: the girl in a long, horizontal swallow-dive that stops a metre from the floor; the pair flying vertically, cleaved together, chest to chest; the simplicity of a folksong, sung with all its verses; and best of all, the pronounced sense of community and trust – probably more efficient than any safety net.

Circusfest: Roundhouse, London NW1 (0844 482 8008) until 8 May, roundhouse.org.uk

Next Week:

Jenny Gilbert finally gets to see Akram Kahn's dazzling new work, earlier hobbled by injury