Will Keen stars in a new revival of Jean-Paul Sartre's Huis Clos, which opens tonight (9 January 2012, previews from 5 January) as part of the Donmar's latest residency at Trafalgar Studios 2.

The 1944 play centres on three people who are trapped in hell, and is the source of the oft-used expression 'hell is other people'. Keen stars alongside Michelle Fairley, Fiona Glascott and Thomas Padden in Paul Hart's production.

Keen’s many other stage credits include Waste, Kiss of the Spider Woman, The Arsonists, Tom and Viv, Five Gold Rings, Pericles and The Coast of Utopia.

What does Huis Clos mean?

It's actually very tricky to translate. It's a legal phrase which means 'in camera', for when you have a trial behind closed doors, but it also literally means 'no exit, or 'no escape'.

Tell us about the play

It was written in 1943 during the occupation of Paris. Sartre wrote it for three friends, and apparently he made the parts roughly equal weight so that they wouldn't quarrel amongst each other! He wanted to put three people in a room together and try and find a way of keeping them in there interminably.

It's in part influenced by the three-way relationships he got into with Simone de Beauvoir, but more particularly it's about the idea that, if hell existed, it being to do with the way that we project what we think about ourselves onto other people. So we're imprisoned by other peoples' opinions of us, and what we believe those opinions to be.

Narratively speaking, very little really happens, but philosophically, dialectically, discursively, there's a massive intellectual journey.

You play Garcin – who is he?

Well confusingly he's from Rio rather than Paris, so we had a lot of debates about how we should pronounce his name. He's a pacifist, who ran a newspaper, and was then shot for his beliefs. What's curious about the narrative is that he's in hell, he's dead, and he's with two people he doesn't know. So it would seem on the surface that he has nothing to gain and nothing to lose. So it's a very curious situation for an actor to be in, trying to find what external needs you have from the other characters. Fundamentally it's about the ever-present need that he and the other characters have for other peoples' judgements.

As an actor, can you particularly relate to that, considering that your job invites other peoples' opinions?

Yes, I hadn't thought of that but it's absolutely true. You do have to develop a kind of bullet proof shield to the good things as well as the bad. Sartre's not saying don't listen to other people, but you do have to keep a strong sense of self.

Would you say Sartre was in some ways pre-empting Waiting for Godot?

I'd say that's definitely true. Huis Clos doesn't get performed that much; it's one of those plays that was incredibly groundbreaking for its time and opened new avenues that other people, such as Beckett, continued to walk down, but was subsequently neglected. It certainly has that nothingness at the heart of it, the sense of waiting. I also think that the context of it being written during the occupation is very revealing, because I imagine that living through something like that would lead to immense soul-searching. The French wartime experience was very different to the British. It think the way that the black-and-white of war can create the ambiguity of occupation is very interesting.

And what about its relevance today?

I think it's a very important play today. As I say, it grew out of the wartime occupation, but it's very easy to lose track of what that time was like, and it's incredibly important that we continue to interrogate ourselves morally. In general it does seem to be incredibly prescient, the idea of our imprisonment in other peoples' perceptions – just look at the influence of the internet.

Tell us a bit about the Donmar at Trafalgar seasons

As far as I understand it, the Donmar has a deal to produce three productions at the Trafalgar Studios every year in order to showcase the work of directors who have come through their training scheme. I'm working with Paul Hart, who is a very bright and very nice guy. The performances are in the downstairs space at the Trafalgar, which I didn't know previously but is absolutely perfect for this play. It's completely claustrophobic and has been miraculously transformed for this production.

What do you think Sartre meant by 'hell is other people'?

Well I don't think he was just saying 'other people are a bore'. For instance, there's a terrifying moment in the play when, at the very beginning, I'm completely on my own, which is utterly terrifying. Then other people come in and the importance of their opinions becomes my punishment. Sartre himself was actually a very solitary type, he liked his own company. It's also worth saying that he was imprisoned during the way and the first part of that time was a tortuous psychological period when he was constantly soul-searching about his own resistance efforts. So he writes from experience and explores the idea that hell is not just other peoples' opinions, but the judgements we make about ourselves.

Huis Clos continues until 28 January at Trafalgar Studios 2.