THE actress Irene Jacob is usually centre stage, or at the luminous centre of the focus of a screen, rather than off-screen, or in the wings.

However, at this year's Edinburgh International Festival, the lauded French actress, known for her acclaimed roles in films such as Krzysztof Kieslowski's Three Colors: Red and The Double Life of Veronique, is not the lead actress, or the centre of the audience's attention.

Not visually, anyway. For in La Maladie De La Mort (The Maladie of Death), which is being performed at the Lyceum, Jacob is the narrator through Alice Birch and Katie Mitchell's update of a testing, intense and intimate story by Marguerite Duras.

The voice of the intense, hour-long play, which is performed in French with super titles, Jacob is both the aural guide, and perhaps the conscience, of a play which comes to the EIF replete with warnings over its explicit and intimate content.

During rehearsals, Jacob suggested the play have a new title. She says, light-heartedly: "I wondered what direction we were going, where it was going next, I said to Alice: 'Maybe I could call it The Autopsy of the Impossible Intimacy' and she said: 'That is so French, that is such a French title!' But that is the deal. It is eight days, a man trying to reach in to touch something, but it is not going to happen, and the narrator is trying to lead the audience towards the story."

The play, based on Duras' psychological thriller from 1982, has been re-imagined for the stage by Birch, recently lauded for her screenplay for the feature film Lady Macbeth and Mitchell, a much respected director. But its heart remains the same as the book: one man, played by Nick Fletcher, has hired a room in a hotel room so that he can spend a week with a woman, played by Laetitia Dosch.

He has lost, or has never had, the ability to feel intimate with another human being: the eight nights in the hotel are his laboratory, and testing ground. In the production, from the Bouffes du Nord theatre in Paris, the stage is also a working set. The actors are filmed live by cameras. Large screens show the images create by this intense and close-up gaze, and sat off to one side in a cubicle, Jacob probes, explains and provokes the man, and woman, with her narration.

Duras wrote the story, a novella, during a difficult period in her life – she was in tumult with her lover, Yann Andrea, and drinking heavily. She was depressed, and eventually had to be hospitalised. The story, a seemingly simple one on the surface, has dizzying depths. Birch has changed some aspects of the story from the original: the woman is more clearly a sex worker, and the man has paid her. This version also tries to further expand the hinterland of the woman, and give her life beyond the boundaries of the story.

When we speak, Jacob is at home in Paris, where she was born. Ms Jacob, who can be seen recently on TV in the Patrick Melrose series, and in the Netflix show The OA, is just finishing lunch with a friend. We talk at length about the play, and her unusual role in it. The daughter of a physicist and a psychologist, Jacob spent much of her youth in Switzerland. Her English is accented but immaculate.

Jacob says: "The narrator in the book is a man, a man who is hoping to touch intimacy, to be able to feel a women, and to understand her. He is having difficulties finding intimacy with someone. This is the starting point. But he is doing it really in a very bad way, and he is really unable to connect. It doesn't work. But what is at stake for him is obviously very important – he is in a very depressive time where he has to reach out to something essential."

Birch, she says, wanted to flip the narration to that of a woman, and she adds: "And the woman in the book is often asleep, and the man is figuring out a lot of things that he may think or do. She is very mysterious, she sleeps a lot. So in this version, the woman becomes very active. We can see her point of view."

Jacob feels the voice of the narrator is almost that of Duras herself, the much-honoured French writer who died in 1996. She says: "The narrator is using a very direct form of address. She is saying: 'You would like to see a woman, you would like to see everything about a woman, but you don't see anything'. So it is the 'you' she is addressing."

She notes: "Duras wrote this book orally. She was dictating the work, and she was dictating to her young lover, Andrea."

She says she is addressing her lover but "she is also drinking a lot, and drinking so much she was in a very fragile state. For me, it is universal. It is about reaching out, about trying to connect, but you don't know how to."

Universal, perhaps, but the man has paid for his female company: there is an old dynamic at play from the start of this scenario. The man is using the woman as a tool.

Jacob demurs. "If you ask me, my take is that this man could have been a woman, and the woman could have been a man. There are male sex workers too, and there are women trying to connect too. I think it is bigger than that. It's about intimacy and two people not being able to do that. It questions what is our intimacy, what is in there that can be so... crumpled."

She adds: "In the end, Duras has very hard words. She says: 'You are always turned towards death, you are not even noticing that you have a woman in front of you. If she left, would you even notice?'"

Jacob laughs, and says at some level the play is a mystery. "Sometimes Katie [Mitchell] would say: 'This is very dark, it is definitely not a lullaby'. This play is such a mystery, and because it is such a mystery, we can only be precise as possible, step by step, because there is something much beyond this. That reminded me of working with Kieslowski too, because he was always so into precision and being specific, being in that particular moment, so that you can touch something beyond something beyond the actual subject of a particular thing. And this case, it is intimacy."

For Jacob, the production, although live, is almost a hybrid of screen and theatre. After all, there are four camera operators on stage. "And the work is very precise because they have to take very precise positions, it's like a film being shot live on stage," she says. "There is a sound engineer, a costume designer changing things, wardrobe and props, you see this whole life on stage, which is not only the story, but the making of the story."

Jacob, 52, has appeared on stage in the West End in London, notably Madame Melville with Macauley Culkin in 2000, and she has more theatre work planned, but she has not performed in Edinburgh before. She may be bringing her son, she says, so that he can experience the frenzy of the Fringe for the first time. She laughs: "You have 200 plays a day? You must have to take a risk."

It is, however, her roles in films for which much of the audience may know her, especially the two masterpieces, in 1991 (The Double Life of Veronique, for which she won Cannes Best Actress award) and 1994 (Three Colours: Red, which was nominated for three Oscars), she made with the late Polish director.

Indeed, she mentions Kieslowski's name several times during our hour-long conversation. "I really love going on a long adventure, and sometimes it is great to come into a film and do this or that, but it is also good to take a long time with a play, and really dig in," she says.

"Right now I have been really living with this woman for a long time. In acting, it is really about contacting with something. On stage, of course, when have a night where you don't find 'it', it can be cruel. It can be terrible for an actress when you try and be connected and cannot. You are late or in advance. It can be so frustrating."

Small victories, she says, can be found in her own performance on stage and in front of the camera. She says one particular moment with Kieslowski has provided much comfort about the vagaries of performance. One day, on set, the director asked her what was wrong. She says: "He said: 'Oh, Irene, what was it today, you were maybe not in good shape.' And I wasn't feeling fantastic that he was saying that, but he said: 'Don't worry because that's the way it is: one day you are in very good shape, and the next day, it maybe it will be your partner in very good shape. Films are made this way: One day you are on top, the next you are trying to find something and not really reaching it, and then you reach it. It is about mixing it all.'"

Kieslowski, she said, told her that if he succeeded in 30% of what he set out to do, he was "completely satisfied." She adds: "I have to say, if I go and see a play or a film, and I am really touched for 20 minutes, then I am really so happy, I am all 'Wow, that is so great.' So I understand Kristof in this sense: you just keep going, just accept it, and try and reach for something real in that moment and hold on to it."

Jacob's husband, Jerome Kircher, is also an actor. "I go and see him many times, and you can see how different each performance can be, from one night to another. And this is what we are – part of the process. Katie Mitchell, when we were making this play, said: 'We have to talk about fear. If something is going wrong, just go to the next step, go to the next moment and leave it behind. We can only try for our best, and if its not working – this line, or this take – you just go for the next one."

Jacob says she had long wanted to work with Mitchell, who is "highly appreciated in France", she says.

"I wanted to see how she would take a piece, and take it somewhere else," she says. "She was criticising it all the time. She was saying, 'You have to be sharp, you have to be precise.' Sharp, and precise, they are really her words! And she was going, without concessions, into some really dark places but I felt that by being so precise she was liberating something."

For the role, Jacob read books about Duras, and listened to hours of her interviews. Ultimately it was Duras' searching voice, and the plight of the woman in the play, that provided the new dimension to the staged version of the story. And Jacob's nameless narrator sees it all, and comments on it all.

In her glass box, "I am not exactly on stage, I am with them, but in a different space." Mitchell said she chose Jacob to be a woman of her age, so she could identify with the narrator. She wants the narrator to pursue "lines of interpretation" that take the audience to another perspective on what they are seeing on the stage.

"For example," Jacob says, "at one point, the man is watching pornography, on a screen – which is again a dimension which Alice Birch wrote, it is not in the book – and you see him watching, and I say: 'There are cries that cannot be reached and wept by you.' The narrator is taking the audience in a different place sometimes from what you are witnessing."

So, she adds, her role is "absolutely vital" to the play. "The narrator is setting the rules of the journey, and the steps of the journey, and the steps are maybe not everything that you see on the stage."

La Maladie de la Mort, Royal Lyceum, August 16-19, Edinburgh