Theatre: FAMILIA Riverside Studios, London

In this strange, Tunisian Bernada Alba-type tale, only three elderly sisters remain from a family of seven. We first see the three old hoydens returning from the grave of the most recently departed, whose exit, like those of the other four, was shrouded in mystery. As they hobble home, the three sisters bicker virulently, in Arabic mostly, breaking every now and then into French: "Salope! Putaine!" they spit at each other. The tyrranical Bahja has discovered that the youngest, Moika, has managed to seduce the policeman in the short space of time necessary to lodge a complaint against the unknown enemy, who may or may not be responsible for the sisters' demise.When they arrive home, the policeman is already ensconced, apparently to investigate the anonymous threats that have been plaguing the women, though the lure of Moika cannot be ignored in his motivations.

The clown-like performances of the three women are devastating portrayals of old age. Director Fadhel Jaibi's desolating vision dictates the grotesque, slapstick comedy which seems to come from either rage or despair. He offers us a glimpse of a culture whose frustrations we can only guess at. The sisters come to symbolise Francophile Tunisian intelligentsia, holed up in their decaying house, surrounded by invisible threat. It is unclear to what extent the threat is real or imagined, or how much the sisters themselves are complicit in it. What secrets are they hiding from the policeman, or is he in turn deceiving them? Why do they collude in their own repression, and why do they turn on each other so viciously, yet not allow any of them to leave?

The sense of repression, paranoia and decay is heightened by Jaibi's striking use of lighting. The stage is always in half-light: shadows loom, lurid light slants in at weird angles. Old-fashioned tango music floats into the locked house, and the narrative proceeds elliptically, with whole sequences of freeze-framed tableaux, in the manner of an antique, silent film.

The use of Arabic heightens the experience of watching this atmospheric, half-understood fable. When the characters slip, mid-sentence, into French, the sudden understanding takes on a greater importance: "Je ne suis plus libre chez moi!" laments the frailest sister Babbouna.

But it is the tyrant Bahja who is the most complex and tragic of the characters. Jalila Baccar never lets slip the relentlessly domineering facade until late in the play, when she reveals the tragedy of her youth. As an aspiring singer, a lover ruined her career. "All I wanted was to perform in public, just once," she says, "but he said, 'if you want to sing, you will sing only for me.' " With the rise of fundamentalism, often a woman's father, brother or lover is her most insuperable obstacle to artistic fulfilment. The sense of thwarted potential is palpable, surpassed only by the coup de theatre of the evening, when Baccar effects a miraculous transformation, before our eyes, into the young woman her character once was. It is a moment of quiet dignity in an evening of stylised excess.