The cult immersive theatre show that’s like a therapy session and fever dream combined

On the night I’m due to attend You Me Bum Bum Train, an immersive theatre show cloaked in so much mystery that I know next to nothing about it, I have reached my December peak. It happens every year: at some point, usually the week before Christmas, my immune system simply gives up. And who can blame it? By this juncture in the wildly ambitious festive social calendar, my body is approximately 33 per cent cheese, 33 per cent prosecco, and 33 per cent whatever Christmas-themed chocolate has been left lying around. I have enjoyed too big a tranche of merriment for too long a time, and now I must pay the price.

So it is that I drag myself across London on a Thursday night, a limping husk of a woman. My throat is sore and gravelly, my nose full of mucus, my head swimming with brain fog. To say I am “not in the mood” to go to a theatrical event described in the otherwise cryptic ticket information as “physically challenging and intense” is as gross an understatement as saying I’m “not in the mood” for a cervical examination. The thing is so demanding that those who could be pregnant or have any underlying medical conditions are forbidden from participating “due to the high risk of harm”. I’ve been dissuaded from coming should I suffer from claustrophobia, told to wear flat shoes and trousers, and warned to expect periods of darkness, nudity, strobe lights, blood and scenes “that some may find distressing”.

If it was anything else, I’d simply sack it off and cry lurgy, crawling back into bed and cocooning myself like the hibernating dormouse I so long to be. But this is You Me Bum Bum Train, a revolutionary theatrical project so under-the-radar-cool yet renowned that you have to enter a ballot to get the £99.99-a-head tickets – the immersive theatre equivalent of the London Marathon. Invoking its provocatively silly-sounding name is like doing a secret handshake; people either look at you like you’re insane or nod sagely, immediately signifying whether they’re a member of the club or not.

First devised by Kate Bond and Morgan Lloyd 20 years ago after they met as art students in Brighton, the boundary-pushing performance piece has only been staged a handful of times since then, scooping both the Evening Standard Award for Outstanding Newcomer and the Oxford Samuel Beckett Theatre Trust Award in 2010. Now, it’s back after an eight-year hiatus, set in a disused building in a secret West End location and sold out for the entirety of its run from the end of November to the end of January 2025. Mucus or no, there’s no way I can in good conscience take a “rain check” on this puppy – it could well be 2033 before I get the chance to experience it again.

I already know writing a “review”, or anything close to one, will be… challenging, shall we say. The press information didn’t leave much wiggle room for interpretation: “YMBBT is different to other productions, in that it is essential that the content of the show remains confidential. This is for the simple reason that we want to preserve the purest form of the experience for future guests. Secrecy around the content ensures that audience members (passengers) are always “in the moment” and not prepared with a staged response, so that its impact will stay with them as a profound memory to draw on in their future lives.”

What this means in practice is that I can’t disclose any information about the experience, “including specific details of what happens before/during/after the show, or information around scenes or themes.” Tricky, wouldn’t you say? But much as I would like to huff and puff about all this Fight Club-esque cloak and dagger stuff, it’s one of the profoundly unique elements of the performance – not only are “passengers” told to abstain from trying to look up information about it beforehand, there practically is no information to look up. Participants really do respect the fact that they’ve been sworn to secrecy (and are even asked to sign something akin to an NDA to that effect); it’s theatre’s best-kept secret since the ending of The Mousetrap.

So, what can I tell you? “Broad descriptions of the format are permitted” – which means I can say that, unlike famed immersive theatre show Punchdrunk, you go into YMBBT alone. You’re the sole audience member moving between scenes in different rooms, immersed in elaborately rendered and painstakingly crafted sets. The attention to detail is sublime – no wonder they leave it so long between performances when the production values are on this level.

Each time you’re led to the next location, you’re plunged into a whole new, completely unknown scenario – relying on “cast members” to guide you through and provide enough information to figure out what the heck’s going on. Well, I say “cast members”, but that’s the other extraordinary thing about YMBBT – everyone you see and interact with is an unpaid volunteer, not a paid actor. And there are hundreds of them, some filling in as extras in the crowd, some with meatier roles. It’s part of the project’s brief: community-building by inviting people in to be a part of the show, contribute, forge new friendships, learn new skills.

Participating in something like this as the “passenger” is one of the purest adrenaline hits I’ve ever experienced. At the outset, the nerves are huge – I walk into one of the first big scenes, sit down, and feel immediately like I’ve been dropped into that recurring nightmare of being thrust onto the stage and realising I don’t know the lines of the play. It’s terrifying; it’s exhilarating. Before I have time to worry if I said the wrong thing though, it’s on to the next one, ushered through a door and thrust straight into another on-the-fly brief. The pace ranges from quick to even quicker, and it’s this hurtling whiplash momentum that makes for an experience of such dizzying highs. It’s on scene four – or was it five? At this speed, who can remember – that I find my rhythm and start to really, properly enjoy myself, each time feeling an even greater surge of excitement about where, and who, I’m going to be next.

It’s like the most exquisite distillation of main character syndrome imaginable – because whatever the scenario, you are the star. For a natural show-off like me, it’s 60 minutes of unadulterated euphoria. But for someone not used to taking up space in that way, I’d wager it’s an even more radical and transformative ride – the chance to be someone important, to be seen and heard and really listened to, to inhabit a world that, for the briefest moment, revolves around you and your decisions. Here, you are Somebody.

There’s shade scattered between the light, too – set-ups designed to make you think deeply without ever being didactic, that by their very nature force you to probe your politics and ethics in unexpected ways. There was an anger that surprised me when dropped into certain roles; empathy I rarely tap into when confronted with certain situations. But again, before I could navel-gaze too intensely, I’d be taken by the hand and led off to perform a totally different star turn in whatever madcap skit was next on the agenda.

An hour has never gone by so quickly in my life. I came out the other side buzzing, all synapses firing, with the thought what on earth just happened? running through my head in an endless, fizzing loop. It was like going through the most glorious, neon-hued fever dream. On hallucinogenics. With a side of therapy.

I was so dazed and overstimulated, in fact, that when I walked past the cloakroom and saw Mamma Mia! Here we go Again’s Lily James and Dominic Cooper standing there chinwagging, my first thought was that this must be another part of the performance. (Spoiler: it wasn’t. They’re obviously just fellow YMBBT enthusiasts.)

Sixty minutes prior, I’d walked into that building a broken woman, ready to call the whole thing off and take a nap on the floor. Sixty minutes later, I walked out of that building feeling shiny and new – still full of mucus, but re-energised, standing taller, ready to go into the world with joyful purpose as the main character in my own life. Perhaps that’s the most surprising thing about YMBBT after all: I finally found a cure for December burnout that actually works.

‘You Me Bum Bum Train’ is sold out for the current run until 30 January, but you can still sign up as a volunteer to be part of the performance at bumbumtrain.com. Walk-ins also welcome.