Neil Cooper and Shona Craven

The Idiot Colony, Pleasance **** Plastic, Pleasance *** Charlie Victor Romeo, Underbelly *** The Factory, Pleasance ***

How sensitive should theatre be to real-life taboos without becoming didactic or resorting to shock or sensory overload? In the case of The Idiot Colony, an impressionistic depiction of three women's incarceration in a mental hospital, attention-seeking tactics would cheapen a delicate work of damaged poetry and slow-moving grace.

This debut show by the RedCape Theatre company starts with a trio of women lined up in a row, their hair covering their faces like they're escapees from a Japanese horror flick. When they come out from under their fringes, we're allowed a glimpse inside their minds from the safety of the residential hair salon which provides sanctuary of sorts. One woman works through the styles of movie femmes fatales and remembers how she had her first orgasm in the cinema. Another recalls a far more brutal sexual awakening. Then, beyond the heightened sexualisation, there's the silent girl who sheds leaves from her hair and spits out jewelled pebbles.

Devised by the company and based on first-hand accounts, such material in less capable hands could have ended up a shrill piece of madwoman-in-the-attic realism. RedCape, though, are more interested in exploring the subtle physical nuances that make up the women's everyday rituals. Under the guidance of director Andrew Dawson, whose Herald Angel-winning Absence and Presence tapped into the intimacies of loss a couple of years ago, the result is beautifully accomplished.

Its precision and overriding poignancy, however, are leavened by the comforts of 1980s pop and a stab at the Birdie Dance before sheer terror takes hold. As played by Claire Coache, Cassie Friend and Rebecca Loukes, the women present some devastatingly effective stage pictures, made even more startling by their horrifying simplicity. One is a drowning, the other a lobotomy. As harrowing as they are, both images point to some kind of release in a remarkable debut that promises much, however heart-rending the subject matter.

Elsewhere, in the new labyrinthine Pleasance UnderGrand space, we're ushered into a pan-Iranian laboratory by the 30 Bird Company, who last visited Edinburgh with The Persian Revolution, a refreshingly complex take on Iranian mores. In their latest work, Plastic, things take an even more opaque turn, as director Mehrdad Seyf looks at a country which has, somewhat surprisingly, become the world's capital of gender modification. So it is that on entering to the sight of women perched on vertiginous heels and dressed in white in the distance, the men and women in the audience are segregated before being led on a promenade through a living installation involving film and sound constructions.

But first, the pickles. Jars of the things line one of the rooms, on the wall of which a film of the actors is projected. We've already been given a loving description of how pickled onions are preserved by a man who then tells of his intention to remove his own sexual organs. Inside, a female voice explains the meanings of her songs through a loudspeaker, before a male voice tells stories that can never be repeated. Elsewhere, a woman has her breasts strapped down in a manner that resembles foot-binding.

In some ways, Plastic is an abstract sibling of Free Outgoing, the India-set play currently running at the Traverse and involving sexual indiscretions made public in a very private country. Coming from a white, western standpoint, at first glance I wondered what all the fuss is about. Here, after all, is a piece of work that takes its concerns very seriously - but those concerns were surely dealt with in Britain in the post-punk, post-feminist, post-separatist wave of radical performance in the late 1970s. In America, too, the culture wars of the 1980s took stuff like this as far as it could go. Didn't they? Put this into a 21st-century Iranian context, however, where as recently as last year the president, Mahmoud Ahmadinejad, denied homosexuality even existed in the country, and you realise why Plastic matters.

At a slender 40 minutes, it's not developed as fully as it might have been, and even here there are too many longueurs between scenes, but it still goes some way to confronting a society where nothing is quite as it seems, including men and women.

Fear of flying is one of life's more understandable phobias. And if anything was to dissuade the casual traveller from spreading their carbon footprint via cheap flights, it's Charlie Victor Romeo, a piece of documentary theatre from New York's Collective: Unconscious ensemble. The premise is simple: to re-enact verbatim transcripts of recordings found in the black-box recorders of a crashed aircraft.

Following a standard demonstration of safety procedures to unusually attentive listeners, the play becomes part disaster movie and part nervous breakdown for an audience nestled tightly in the economy class of the Reid Concert Hall, as events on stage veer towards the voyeurism of "death porn" as seen on late- night TV.

Over half a dozen amplified scenarios, ranging from an extended battle with equipment to a brief and scarily Hitchcockian attack by birds, the tension mounts. You're willing the cabin crew, here occupying a set that looks oddly like a disembodied plug socket, to land safely, even though you can already guess the painful inevitability of each flightpath.

It's an easy but sweatily effective trick, and one that's already been used as a training demonstration for new aircraft crew. Getting back on to terra firma has never been such a relief. NC THE guard is only an actor, of course. But he's brandishing a metal bar, so it makes sense to shut up, move and face forward, as per his every barked command. From behind us, two very loud bangs and a woman's scream. The audience flinches, but before too long we'll be accustomed to both sounds.

Badac Theatre Company's uncompromising production, The Factory, staged in the underground caverns beneath the Pleasance, is not a ghost tour. It's not about cheap scares, nor is it about whispered poetry or especially profound insights into human fear, panic and despair.

It is an invitation to retrace the final steps of Holocaust victims, and surrender to the resulting sense of overwhelming sadness. Think carefully about whether you want to experience it, and don't even think of booking tickets for another show that starts straight after it.

The dialogue is simple and repetitive, as are the meaningless physical tasks undertaken by a menial worker with a crumpled face and haunted eyes who is coming close to breaking point after sending hundreds to their deaths.

To call this production a "promenade" seems wholly inappropriate, evoking as that word does a leisurely guided stroll. The audience is ordered from room to room, eventually filing into a confined space from which it is clear that three people will not be walking.

They are only acting, of course. But they are also naked and covered in sweat, dirt and snot. Their loss of dignity does not feel artificial, and when they begin to sing the Israeli national anthem - proudly, defiantly, urgently - the scale of the suffering they represent becomes overwhelming.