Companies such as Sound And Fury have long been experimenting with the dimmer switch and only last year the Festival introduced us to scratch-and-sniff theatre with a show in the Marine Colonnade toilets.

If you've ever been to an over-subscribed school production, you'll also be familiar with the notion of action spilling over from the stage.

But you're unlikely to have experienced anything quite like Zygo's production of The True History Of The Tragic Life And Triumphant Death of Julia Pastrana, The Ugliest Woman in The World, which takes over the theatre's balconies and aisles, plunges the venue into total darkness, and fills it with the smells of rose water, hospitals and Mexican cooking.

First staged in 2002 and now revived for the Festival, the play tells the true story of Julia Pastrana, a 19th-Century Mexican peasant sold into a travelling freak show.

Known as the Ape Woman, Pastrana suffered from excessive body hair and enlarged gums, and here finds herself advertised alongside the "boy with a face like a fish" and "the man with elastic skin".

What appears to be exploitation has unexpected results, as she makes friends within the carnival community, becomes famous and - unlike most other women at that time - earns a decent wage. But, as the uncut title reveals, Pastrana's life soon takes another tragic turn.

In pursuit of "juicy, pulsing, living, breathing theatre", Brighton's Zygo company have always pledged to "pull any trick in the theatrical book". But when the idea of staging a play in total darkness was proposed, director Andrea Brooks says she "scoffed at the idea".

"I'm a physical director and I tell stories," she says. "I didn't want any of that nonsense."

When she mentioned it to playwright Shaun Pendergast, however, his face lit up.

Long obsessed by the story of Pastrana, he had never been able to figure out a way of staging it - it was too huge and theatrical to be a radio play, too visually demanding to stage.

Here was the answer, and it made sense for the character, too - "Pastrana wasn't allowed out unless she was performing," he says. "She spent so much of her time in the dark."

Conveyed by Brighton's Zygo company using only sound, smell and the poetic surrealism of the script, The True History promises to be a piece of boundary-breaking theatre in which "nothing is done just to be clever", a resurrection of the Freak Show which asks where ugliness and beauty truly reside.

As if that weren't experience enough, this Festival run will also see the world premiere of another Pendergast play, for which the lights will come on. A short piece more comic in its blackness, The False Corpse will bring you face-toface with a Victorian comedian, a gun, a rubber chicken and his death wish.

Starts at 7.30pm on May 17, times vary on other nights. Tickets cost £10 - £18.50, call 01273 709709.