SELINA CARTMELL is oh so up and coming. Or maybe that was last year. Yes. Selina Cartmell is oh so arrived.

When the Gate's Michael Colgan accepted his gong for producing Sweeney Todd at the recent Irish Theatre Awards, he more or less dedicated it to Cartmell. She has a muse, Olwen Fouere (eight productions together), and now she has a playwright too, Marina Carr.

Fiach Mac Conghail at the Abbey has taken her in. Later this year she goes to the RSC. She even has a mentor, or something, under some philanthropic scheme.

And she's very young. I forgot to ask, but she looks about 22, and only left university this century. It's all very tedious. I couldn't possibly like her.

And then she keeps me waiting.

Her crew treat me with the kind of respect normally reserved for sex offenders, while Cartmell "finishes up" for the day. No, I can't take a peek; they don't have the authority to interrupt her to ask. "Selina's always running late, " says her assistant, "she works soooo hard."

Hours pass. Nobody offers me tea. Eventually, at 6.15pm (our interview was scheduled for six), I'm tentatively ushered into the theatre. Cartmell is busy in conversation. I hang about. I eye up the set. I take out my mobile phone to take an aide-memoire snap of the theatre. Suddenly the assistant is beside me. "Selina doesn't want any photos taken of the set before it's ready." I put away my mobile phone.

More hours. 6.20pm.

Eventually, Cartmell dispenses with her cast/crew and ambles over, looking warily out from under a baseball cap.

By 6.23pm, I am under her spell. She doesn't say anything particularly original or brilliant, but she is smart, passionate, and understated. She wears her precocious success lightly. She thinks about questions as if she is unused to being interviewed. She seems honest, and potentially vulnerable. I like her a lot. How tedious.

Selina Cartmell started life in the terrifically English village of Ickleford in Hertfordshire, which Wikipedia tells me has a primary school, a general store, a village hall and four pubs, The Plume of Feathers, The Olde George, The Green Man and The Cricketers.

She remembers seeing her brother in a school production of Billy Budd, and being brought up on stage, aged six or seven, in a production of The Golden Egg.

Something bit.

By the time she left school, she was directing plays. She studied history of art and drama in Glasgow, and interrupted that to spend a year at Trinity, in 1999.

She followed her BA with a masters in directing at Central in London. Soon after that, she was back in Dublin. By 2003, she had won her first award, a 'best production' prize in the Dublin Fringe Festival for La Musica. In 2005, her production of Titus Andronicus won four Irish Theatre Awards, and opened the doors to the Gate (Festen, Sweeney Todd) and the Abbey (Woman and Scarecrow) to her. In 15November, she directs a new Marina Carr play, The Cordelia Dream, at the Royal Shakespeare Company. The Arts Council has given her 100,000 for this 18night run of Macbeth. She appears to think this is all fairly normal.

It's been "two years!" since she last worked with her own company, Siren Productions, she says. Two years! And all she's done is a handful of plays at the Gate and the Abbey and an international mentoring programme. What a slacker.

She talks about "creating Shakespeare on a shoestring budget" and having "only five weeks" rehearsal time. "In an ideal world I would have my own space, with my own company, creating works over long periods of time." She has no careerist ambitions: "I don't have any major 'I want to be there in five years time' thing. The most important thing is to have the mutual respect of artists."

She is earnest and perhaps even naive. But she is also formidable: her productions are assured, visceral experiences, and they have persuaded some of the most significant people in Irish theatre that she has real substance. Her apparent naivety may yet turn out to be vision.

Dublin needs a theatre company that has its own space. Watch this space.

The themes of Macbeth persist, she says: "corruption, power, ruthlessness, passion, sex, love, death, life". She doesn't have to put the stamp of politics or current affairs on the play for these to come out in rehearsal.

"Every day, we talk about politics in this room. Every day, an actor talks about something that's on the front page of the newspaper."

This space, where we are talking, was what impelled her to do Macbeth, a play she has always wanted to tackle.

"It's subterranean; it's got stone walls and an earth floor. It can be the heath, Macbeth's castle. It can be any country in the world. And yet it's universal enough to become our space too."

This is the Empty Space, a theatre on the site of the original Theatre Royal Smock Alley, at the west end of Temple Bar, near the Civic Offices. It has recently been taken over by Michael Scott's City Theatre, and is hence enjoying a new lease of life as a venue for hire.

"It's a ghostly place. It started me thinking about the play as a play for the dead. As if they've been wandering this space for centuries, and they need to do this play to move onf" The play is steeped in "fear and terror", she says, but she won't be turning it into a gore-fest: her approach is to "allow the audience to use their imagination, rather than to spell it out".

"Shakespeare leaves massive unanswered questions. The audience are like detectives in a murder mystery. Shakespeare paces it like a thriller." The production is two hours long, runs straight through without an interval, so the audience can't escape.

"Once you're in this space, why would you want to leave it?"

Cartmell's bias is towards these kind of "found" venues, or site-specific theatre . . . currently a big vogue in the UK. Titus Andronicus was originally to be staged in a disused cash and carry on Thomas St; when that fell through, she hoped to do it in the Iveagh Market. Ultimately, health and safety forced her back into the Project Arts Centre. In the Empty Space, she has found the perfect compromise: an "official" theatre space, but with an aesthetic that's a cross between a building site and a cemetery.

That sounds unconventional, but her approach to Shakespeare in fact is deeply traditional . . .

though this is, paradoxically, a tradition that has been neglected.

"The audience has to walk through this space to take their seats. They feel implicated.

They've stood on the very earth where the characters are going to be performing a very bloody play.

The language is murky and dense at times; the key to it is to have that close proximity to the audience.

"The audience goes on a rollercoaster journey with the actors rather than watching from a distance. They have to be able to experience it viscerally, visually, physically. They have to be able to smell it, feel it."

And she is intensely aware of the challenge of the verse, and of the need to get it right.

"You really need to understand what you're saying. You can always feel it when it becomes 'flabby', when you're stumbling through and haven't a clue what you're saying. The verse only starts really living in an actor four, five, six weeks in to rehearsal."

After meeting Cartmell, I come across an article by Dominic Dromgoole, the artistic director of Shakespeare's Globe in London, in the Sunday Times, arguing that much of today's theatre forgets what it's there for . . . to share a story with an audience.

"In the spread sunshine of the first theatres, the actor would have to look into the eye of the spectator, standing or sitting in the same democratically shared light, and sell his joke, or sing his song, or tell his tragic story, " he writes.

"The realism of these theatres . . . and they were shockingly real, in their own way . . . was not based on sets or lighting or sound: it was based on the inescapable honesty with which the actor fixed the audience's individual and communal eye, and told them that what he was saying was realf "Any brief amount of time spent in the Globe, where I am lucky enough to work, opens one's eyes to the rough grace of theatre that does not dictate a story, but invites an audience to share in it.

"The audience is the heart of a theatre event. Ignore them or, worse, just try to impress them and the heart will be concealed.

Address the audience and the heart of a theatre event will be revealed. Where theatre does that, it has a future."

He says it better than Cartmell, or than I could. But Cartmell has found a venue with its own "rough grace", and she has the insight to place her audience at the heart of her theatre, implicated in it. Those two hours should pass quickly.

Macbeth runs at the Empty Space Theatre until 15 March