The Duke of York’s Theatre is an intimate little place somewhat hidden away in the bustling heart of London; as such, it’s the ideal venue for this new adaptation of Henrik Ibsen’s An Enemy of the People, starring Eleventh Doctor actor, Matt Smith, a production which is in your face, caustic, mesmerising, confrontational, uncomfortable, and utterly shocking.

One of the things that an audience immediately notices is how the lights stay on throughout 95% of the play. It’s intimidating but also incredibly immersive, and if you think that makes every audience member an intrinsic part of the play already, just wait until Act Two.

Smith plays Dr Thomas Stockmann, medical officer for the town’s baths. It’s an important role, belied by the fact his brother, Peter (Paul Hilton), is mayor so, it could be argued, got him that job in the first place. Keeping it in the family. But Stockmann is more than qualified: smart, passionate, and intuitive. The town relies on the baths and their healing properties, so a lot rides on Thomas’ say-so. And that becomes a massive problem, underestimated by Stockmann, when he investigates reports of bathers falling ill; indeed, the water is poisoned:  E. coli, legionella, vibrios – you name it, the water’s probably got it. Thomas is just happy that he’s the one who’s found the problem and can help address it, bringing the truth to the masses!

But of course, it’s not as easy as that. The spa is privately owned by shareholders, and they’ll kick up a fuss at it being closed for what’s estimated to be at least two years. And they own the spa, not the water; that’s owned by the people of the town, who might not be too pleased at having their taxes raised in order to pay for relocating pipes and collection tanks, at the cost of around £100 million.

But as Stockmann says, he wouldn’t know how to work out the cost of these things: it’s just his job to “clear the swamp” and tell the truth.

The play starts off with a simple truth, then distorts it, winds it around, and, rather appropriately, muddies the water. Thoroughly.

It’s organised chaos, at times comedic, at others horribly affecting and traumatic. And it’s absolutely brilliant.

Much of the comedy is left to Billing (Zachary Hart), an employee at the local newspaper with designs above his station. He wants things to change, but whether that be for the people or for himself… Well, that’s his big question. Nonetheless, he’s personable, happily chatting away to someone in the audience, becoming the face of the everyday man, it seems. He welcomes you in, in a way no other character really does – not even Stockmann, a man of the people, but who is more content to butt heads with you (and his brother) if he believes it’s right to. Even so, Matt’s considerable talent means you’re always rooting for him, always believing he’ll do what’s right in the end, no matter the consequences, and always the one who draws your eye, even when he’s barely moving.

Doctor Who fans will recognise Smith’s energy and passion, his incredible ability to be both frantic and still. So too his clumsiness – in the performance, my friend and I saw, he ran into a wall, hurting his knee, causing concerned utterances from his peers, but carrying on nevertheless. You suspect the cast is more than used to this. And it gives Thomas an extra bit of charm, as if his manic mind, combined with his intense focus, affects his whole body. There is, it’s impossible to ignore, an energy about Matt – on TV, yes, and certainly on stage.

I read the script for Thomas Ostermeier and Florian Borchmeyer’s adaptation and it’s astonishing to see how much focus there is on Matt’s Dr Stockmann; how many pages of dialogue he has to deliver in such an impassioned way; and how Smith brings this character to life using, it feels, many of his own viewpoints that he seems to share with the lead. He is simply one of the best actors I’ve ever seen.

But then, the cast all get a chance to, as actors, shine, and, as characters, dim. The situation means that no one comes out of this unscathed, their true colours coming to light in the darkest of situations. And thanks to the audience being a key part of the production – members of the town hall meeting called to discuss the matter and invited to share their opinions on Dr Stockmann’s rather spiralling but compelling rant against the real poisons affecting society – we, by extension, become lost in this miasma too.

It helps that the cast watch part of the second half from the aisles, throwing insults at Thomas, who stands above them all at his lectern; they make eye contact with people in the theatre, as if challenging them one minute then trying to convince them that they’re one of them, one of the crowd, one of the majority. They’re telling us they’re on our side, even if we know differently.

I particularly enjoyed seeing Katharina Stockmann (Jessica Brown Findlay), recording her husband’s magnetic diatribe against our everyday lives on her phone. Yes, we may rail against social media, but we know its value.

Kudos, especially, to Priyanga Burford, who plays Aslaksen. She opens up the town hall meeting for debate and is left to field the audience’s own grievances. Though Stockmann acknowledges his hypocrisy, being a key part of a society he apparently despises, an audience member when I attended still noted down the cost of tickets to a play that seemingly attacks capitalism. (Not entirely fairly, it has to be said – in publicity for the play, Matt said he was proud that the theatre did have cheaper seats available so the messages could be spread.) Aslaksen seemed shocked and met this complaint by saying, “I’m sorry, did you have to pay to get in here?” and highlighted that this was a town hall meeting, not a theatre…

And it’s not right to say that An Enemy of the People laid into capitalism entirely either; rather, it criticises all political leanings, summing up that they all amount to the same thing. This isn’t a liberal fantasy: it’s a fantasy that critiques liberally – and at that, a fantasy that isn’t too far removed from reality. You can see this happening all the time. There’s an undercurrent to An Enemy of the People that’s a reflection of the undercurrent of reality.

That undercurrent explodes, inevitably, into violence once Thomas appears to be getting the upper hand. It’s horrific to see; made worse by the fact we, the audience, feel part of that violence, thanks to the nature of the production, of the lights being up throughout, of the cast mingling with the viewers, of the intimacy of the theatre, of Dr Stockmann’s appeal to us to see the truth.

The narrative begins from a simple point of one person trying to do good, but turns on a knife-edge when that man is backed into a corner at every point. You can’t see the light at the end of the tunnel and often doubt there even is one. You’re left still wondering if the walls, now spattered with black and yellow and white paint, will ever really come clean.

You can buy the scriptbook for this adaptation of the original Henrik Ibsen now.