Séance can be found in a container in the yard in front of Summerhall. I sit on the sceptical side of the fence when it comes to the life after but some part of me would like to be convinced. Having said this, the idea of a séance makes my skin crawl slightly. What if the dead did send me a sign? Maybe it’s this morbid curiosity that draws an audience – as this show is selling out multiple performances already.

As I waited for my turn in the container to a boisterous soundtrack of thunderous groans issuing from the perfomance in progress, I felt distinctly uneasy. Assisted by the fact that the Summerhall helper I’d just spoken to had gripped my arm and told me that the show was terrifying. “But you’re lucky,” she said, “you’re seeing it in the day when it’s light. I had to come out of it at night.” Then one of the audience members burst out of the container mid-performance looking dazed and apologising that he suffered from claustrophia. My heart thumped in uneasy sympathy.

I’m spending too long setting this up because I can’t tell you anything about the twenty minute show without spoiling it. It is unbelievably, stupendously suspenseful. By the time I took my seat – and yes, there’s a long table and a white table cloth and occasional considerate (dim) lamps hanging from the ceiling – I was fully expecting to have to take my headphones off mid-show as you’re advised that you can if it all gets a bit much.

You sit. You put a set of headphones on. You’re told to put your hands on the table. The lights go out and it’s instantly darker than a starless night in the remotest countryside. And you’re off.

The care and attention given to this production by Darkfield is stunning. The sound design is exceptional. The set is just the ticket. And the experience? Suffice it to say that I was so terrified that I disobeyed the instructions given. I was worried that screaming would interrupt the experience for the rest of the audience. Now I’m a susceptible girl, I sometimes struggle with a thriller and Guillermo del Toro is as about as close to horror as I get. So you might not find it quite as terrifying as I. But it’s a delightful terror. You know it’s not real. You’re pretty sure it’s not real. And yet, as the man says at the get go, there’s some portion of you that really yearns to believe.

There’s a fair amount of theatre that claims to be immersive these days. This actually is. If you’re not repulsed or offended at the concept, it’s twenty holding-your-breath, heart-racing, slightly nervously sweating minutes out of your day. And I’ve never experienced anything like it.