If you were to find yourself at 10pm on a Saturday night in a Welsh stately home standing around a magical symbol, chanting, with a black hood on, while a person in the centre of the circle is possessed by the souls of the dead and writhes in pain, you might ask yourself questions like ‘How did I get here?’, ‘Where did I go wrong?’, and ‘What the hell was in that cocktail?’

But fear not! You are not tripping balls, you have not eaten some bad shrimp… you have simply found yourself a guest of The Key of Dreams, an incredible, visceral, 24-hour immersive theatre experience set in a Lovecraftian occult dream world, in a beautiful Welsh manor called Treowen.

My wife and I arrived at midday on Saturday, excited and intrigued. Before our visit, emails from the Friends of Miskatonic University had recruited us to investigate strange goings-on at the house. We had completed questionnaires about our interests, fears, and reactions to imagined situations. Waiting in our bedroom were beautifully bound red field guides, maps, correspondence, and invitations to secret societies. Different secret societies. Apparently, my wife and I would be pursuing different interests during our ‘romantic’ weekend of occult intrigue and discovery.

My letter included an innocuous question and a particular response, allowing me to identify fellow society members discreetly. Unfortunately, this relies on people actually reading their letters. I spent a while asking everyone the same question and receiving perfectly ordinary answers, before spotting a familiar piece of paper sticking out of another guest’s book and gently suggesting she might want to read it. Espionage is harder than it looks! 

There were just 14 guests and six cast members during our visit, with this enormous house and its grounds to explore. We were asked to put our phones away, and ours stayed in our bedroom. I didn’t miss mine even once. There was far too much happening in front of me to give it a moment’s thought.

The manor’s residents are an intriguing bunch. Our host, Wyn Haffenden, has inherited a house he now cannot leave. Expedition leader Dee has a painful history with Lavinia, the warm but unsettling woman who greets us on arrival, and whose resurrection after 20 years raises rather more questions than it answers. Then there is Randolph Carter, a man whose motives I spent much of the weekend trying to pin down. Everyone has information. Whether you should trust it is another matter.

A tour with Wyn introduces the house’s history. I found out later that, with the owners’ permission, the writers had incorporated Treowen’s real history into their fiction, giving the stories a weight that would be difficult to manufacture. You hear about strange events in the place where they supposedly happened, then wander off to investigate them yourself.

Creative director and designer Ivan Carić and lead writer and designer Laura Langrish have created an astonishing amount to explore. You can question residents, compare discoveries, and get involved in competing agendas, or sit quietly working out how to open a mysterious wooden box. There is no single correct way to experience it. I particularly enjoyed finding clues that helped other people’s investigations along.

At one point, I noticed some beautiful wooden masks in the banqueting hall. Turning them over revealed anagrams, which led me to a hidden note connected to a story that another guest was working on. That thrill of finding something, understanding it, and realising who needs it becomes wonderfully addictive. Before long, you are hurrying through a stately home looking for someone you met three hours ago because you urgently need to tell them about the back of a mask.

Marianne Wilberforce’s beautifully made wooden props, alongside Sarah Binney’s puzzle design, make these discoveries especially satisfying. Wilberforce also plays Sophie, a reassuring presence who offers gentle nudges when you are stuck, leaving you the pleasure of getting there yourself. Co-designer Langrish appears as Gillman, a representative of the legal firm keeping an eye on proceedings, adding official business to this increasingly peculiar gathering.

For all the ingenuity of the puzzles, though, it was the performances that made the weekend extraordinary. One of my favourite things about immersive theatre is finding yourself alone with a character and realising that this performance is entirely yours. When I asked Dee about Lavinia’s death, Emily Carding took me for a walk around the gardens and told me what had happened. Their account was full of grief, fear, and lingering pain. I had asked a question as part of an investigation and found myself listening to someone relive a devastating experience.

Carding is exceptional throughout. Later, watching them channel a succession of different presences, with startling changes of voice, physicality, and emotional state, was astonishing. But it mattered because Dee had already become someone I cared about. Carding, also credited as creative associate, makes the most outlandish parts of this world feel painfully believable.

Heather Rose-Andrews is equally compelling as Lavinia, balancing warmth with the persistent feeling that something is not quite right. She can be welcoming, serene, and apparently kind, while leaving you unsure what lies beneath. Other residents have strong opinions about her, but her company makes those opinions harder to accept without question. When that composure shifts, Rose-Andrews reveals an impressive range. Some of her scenes with Carding were among the weekend’s most gripping.

Dan Osbaldeston gives Carter a serious manner with a dry comic edge, making him enjoyable company even when you suspect he is manipulating you. As the resident connected to my society, he was someone I returned to regularly, without ever quite figuring him, or his ‘murder board’ of clues, out. Rik Sowden brings a lovely formality to Wyn’s hosting duties and an enthusiasm for the house’s history that makes him an excellent guide. Then the sadness slips through – hearing him talk about the life he cannot return to, particularly his dog, was unexpectedly moving.

The commitment to character is remarkable. I left a room where Dee and Carter were having a heated discussion, and the argument carried on behind me. Nobody paused because their apparent audience had gone. Someone might still be listening from the corridor, so the world kept going whether we were watching it or not.

Ben Reid’s composition and sound design, supported by Steve Arch’s electronics and software, contribute beautifully to that living world. Old-fashioned radios play music that feels comfortably at home, until you gradually realise something more unsettling has crept in as a scene develops. I never saw anyone obviously operating anything. The house simply seemed to know when to change the mood – though I suspect stage manager Kirsty Arch may have been involved!

By dinner, we were thoroughly absorbed. The suggested dress was ‘timeless’, with the option to dress up for the evening. I wore black tie; my wife wore a ball gown. There is something enormously satisfying about sitting down to a feast in a Welsh manor, dressed for the occasion, while people argue about the wisdom of occult rituals.

Executive chef Dominic Zeal’s delicious multi-course banquet was a highlight, followed later by cheese and desserts, with excellent cocktails adding to the pleasure. Lunch, afternoon tea, and breakfast gave the experience the rhythm of a generous country-house stay. The hospitality was every bit as considered as the theatre, even when dinner conversation took a turn towards possession!

An argument between Dee and Carter during dinner had me grinning at the sheer theatrical joy of it, even while taking their disagreement seriously. Later, one guest became passionately insistent that Dee’s own wishes should be considered. She was defending someone she had come to care about, and the actors gave that contribution space while adapting around her.

The guests helped make this world convincing because everyone was willing to believe in it together. I love Phantom Peak, my favourite immersive experience in London, where you explore, make discoveries, and interact with a wonderful cast of characters. But there are hundreds of guests, some throwing themselves into it wholeheartedly, others happy to wander and observe. At The Key of Dreams, all 14 of us had committed to spending 24 hours in this world. One guest had travelled from the United States to celebrate a 40th birthday. With some of the world-building underway before we arrived, it took no time at all for strangers to be sharing discoveries, debating what should happen next, and worrying about people who technically did not exist.

I won’t explain how those investigations led to the scene described at the beginning. But by the time I was standing there in that hood, none of it felt remotely like an odd way to spend a Saturday night. There was urgent business to attend to.

After the evening’s drama came drinks and a wonderfully sociable wind-down. Then, after sleep and an excellent breakfast, the story continued. The previous night had taken its toll on the residents, with changed relationships and frayed emotions carrying through into the morning. There were still discoveries to make and matters to resolve.

My wife wondered how our arrival could possibly have been only the day before. It felt as though we had been there for weeks, in the best possible way. Ordinary time seemed to have stopped somewhere outside the front door.

This is a substantial purchase, and I wouldn’t pretend otherwise. But the scale of the work, the intimacy of the performances, the food, the setting, and the sheer amount of experience packed into those 24 hours made it feel like extraordinary value. I left with the feeling that we had spent the whole weekend in a parallel world full of mystery, where we had barely scratched the surface of what was possible.

The Key of Dreams is strange, thrilling, moving, and often unsettling. I went to Wales expecting an adventure and came home with memories of people I had helped, secrets I had uncovered, and a house whose mysteries are as profound as its beauty. The residents may be desperate to leave Treowen, but personally I cannot wait to return.

The Key of Dreams takes place at Treowen Manor in Monmouthshire, Wales, on selected dates throughout 2026 and 2027. 

Book your tickets at thekeyofdreams.co.uk. 1883 readers can get 23% off using the code SINISTER at checkout.

Words by Nick Barr

Photography by The Key of Dreams