Olwen Fouéré returns to the stage this week in an imaginary journey that echoes recent events in her own life, she tells Arminta Wallace

Thomas Street, Dublin. Sunny Friday morning. Street traders in T-shirts calling cheerful greetings to customers; shopkeepers sweeping the footpaths; people with plastic bags browsing and chatting and drinking coffee. Life: it's bursting with it. Stepping into the Digital Hub, therefore, is something of a shock. It is vast, cavernous and silent, a black-and-white universe of concrete, neon, and mysterious dark corners.

"Isn't it just extraordinary?" exclaims the actress Olwen Fouéré, raising her arms in affectionate salute. "It could be anywhere, any time. It could be the catacombs."

No offence to the Digital Hub - it's a fantastic exhibition and performance space that, with the right lighting and a spot of imagination, could be the gateway to Hades.

This kind of life-meets-death contrast, and this kind of spatial and temporal ambiguity, is precisely the artistic territory in which Operating Theatre, the company that Fouéré founded with the composer Roger Doyle in 1981, has always been interested. But the theatre piece they are currently rehearsing here has been particularly influenced by the idea of parallel worlds.

Passades, Fouéré explains as we walk around the spaces where the action will take place, will be a journey of the imagination. A lone explorer, played by Fouéré, is trapped in a fragment of time. No words, just visual images and a continuous 50-minute musical score.

The title has a plethora of meanings. It can describe a dance or a brief flirtation, but "Roger's score interprets it as an equestrian term, a sort of musical dressage, if you like", says Fouéré. "And for me it has resonances of passages, thresholds, moving backwards and forwards, the passage from death to life and life to death."

Which, she adds calmly, is of special interest to her, because just a few months ago she had to face the possibility that she might die.

The story is a shudder-inducing one, although she tells it almost matter-of-factly. On a Sunday evening at the end of January Fouéré was wheeling her bicycle across the road at a set of traffic lights in central Dublin. Halfway across the lights changed - and so did her life. She was struck by a jeep and dragged along the ground for some time before the driver realised what was happening.

"After the first impact I remember thinking, well, that's fine: he'll stop now and I'll just have a bit of a bruise. But it kept going on. I was underneath, bouncing along like this - boom, boom, boom - and wondering if he had seen me at all. At the time I was convinced that I didn't pass out, but now I think I did, because the next thing I remember was trying to get up and people running towards me, saying: 'Don't move, we've called an ambulance.' I could already see my face starting to balloon out like this" - she gestures rapidly outwards from her left cheek - "and I could see a white bulge sticking out here in my leg. Pure white - and I was tanned."

Fouéré was brought to St James's Hospital, where the staff worked late into the night, dressing her injuries, doing tests and taking X-rays. At one point there was a suggestion that her skull might be fractured. "So I was lying there, looking up at the ceiling and thinking: I haven't phoned anybody. I might die here. Not how I expected it but, you know, this is how it is. Am I ready to go?

"I was quite calm, but I was fearful of crossing the threshold into what might be my own death. I wondered, How will it happen? And will I know? I didn't want to go to sleep, in case I didn't wake up."

Fouéré's description of her subsequent struggle with serious injuries and a stubborn infection - the white bulge referred to above, in case you were wondering - is heart-stoppingly graphic.

But she is not telling this compelling tale to elicit sympathy; on the contrary, she has reservations about telling it at all, in case it might impact on matters of insurance and suchlike. It has already, however, made a major impact on her work as an actress - and especially on Passades.

"I saw and heard the most amazing things during my time in hospital," she says. "I can't really articulate what I learned, but it was something very fundamental about pure human contact. In the A&E department there are people on the faultline of crisis all the time. Even on a normal orthopaedic ward patients are often living in a reality that's completely other. Being able to meet them in that reality, instead of just drawing back and saying, oops, this person's crazy, was very fulfilling for me. I felt that, just by sitting by their bed, talking to them, I could travel there with them.

"There was one woman whom I'd go up to and I'd say, 'Well, what did you do today?' And she'd say, 'Ah, sure, I was out most of the day,' when in fact she had never left her bed. When I was first brought on to the ward this woman had yelled and screamed and shouted at me. It was quite frightening. To find a way of penetrating that, to the point where I became someone she felt very safe with - all of that was extraordinary."

It is hardly surprising that this lengthy process of dislocation and healing has made its way into Passades. Operating Theatre - the name, under the circumstances, brings a wry smile - had always intended to produce theatrical pieces in which music would be the core element. This time it has succeeded.

"The score of Passades was composed using a particular type of software which captures a sound - one tiny sound - and the whole composition is made within this tiny fragment of sound, which is thrust backwards and forwards," explains Fouéré.

Selina Cartmell, the director of the piece, examined the company's back catalogue and found that many of its pieces related to the idea of an other-worldly journey or tapped into ancient mythology in a contemporary way.

"So those themes were there already. But I would hate to limit Passades to that," says Fouéré, "because it has lots of other aspects to it as well. It started, in a weird sort of way, to tap in to those fragments of time that were missing for me when I passed out - you know, those fragments of time where you go missing? Or general anaesthetic, which, for me, was like a descent into the underworld. It's a moment in time. It's not like sleep. No dreams, nothing, just poof, you're gone. It's kind of like a death, really. And, of course, at a practical level it is the only genuinely life-threatening aspect of many operations."

Thus Passades also touches on the idea of exploration - and of hypothermia, an apt theme for the Digital Hub, where, even on a sunny April morning, temperatures are noticeably cooler than those on the street outside. The production flirts with leitmotifs of archaeology and excavation. But above all, for Fouéré, it has brought her back to theatrical life.

"It built up my performing being again," she says. "I still forget about the kind of stamina you need to do a show. They've measured it: the effect it has on your body is something like the equivalent of doing a parachute jump. This experience has changed me so much that there were times when I wondered was my performing being still the same or did I just want to go and grow tomatoes in the west of Ireland. Now I know. Yeah, I can do this."

Passades is at the Digital Hub, Dublin, from Thursday until Saturday, with performances at 7.45 p.m., 8.45 p.m. and 9.45 p.m.