In a windowless room lined with coffins, 50 people wait expectantly. A stern man in a suit welcomes us. We’re free to explore the mansion, he says. We’re to make ourselves at home. He offers us tissues, which he says we may need.

“Oh,” he adds. “There’s also been an outbreak of tuberculosis. So you’ll need to wear a black facemask at all times.”

With that, couples and groups in the crowd are split up and ushered through different doors into a purpose-built tangle of rooms and corridors, where innumerable little scenes and mysteries play out.

It’s hard to summarise A Midnight Visit, an immersive theatre show staged in an abandoned warehouse in North Melbourne. It’s part mystery play, part haunted house and part art installation. And there’s a bit of cabaret thrown in. The hierarchy of those elements comes down to you, the audience member. There’s no single, linear thread. Visitors walk freely, explore and interact with the cast, and make their own path.

“We’ve attracted a lot of people who don’t consider themselves theatregoers,” says show director and co-creator Danielle Harvey. “They might not go home and think they just saw a theatre show, but they have. This is absolutely theatre.”

“There’s no right way to experience these things,” adds the show’s other parent, creative producer Kirsten Siddle. “People are very much choosing their own route. But we think about how scenes fit together; what people might get from them. Or if you emerge from one room, what might beckon you from there. We’re always changing things up.”

Both Harvey and Siddle have considerable experience producing theatre and art. Siddle has worked for institutions all over the world, from Melbourne Recital Centre, where she was director of programming, to production manager and producer roles at the Barbican Centre in London. Harvey’s spent time as executive producer at the Sydney Gay & Lesbian Mardi Gras, and as head of contemporary performance at the Sydney Opera House. A Midnight Visit Melbourne is the third iteration of the show, after last year’s five-star runs in a Sydney warehouse, and in a heritage-listed girls’ school in Perth.

The common factor in all of those interweaving storylines is the work of 19th-century American writer Edgar Allan Poe, author of stories and poems such as The Raven, The Masque of the Red Death and The Tell-Tale Heart. You might know more Poe than you think, and plenty that you don’t know will seem eerily familiar. His fingerprints are all over contemporary horror and science fiction, and he pioneered the modern detective format in his short story The Murders in the Rue Morgue. A Midnight Visit draws heavily on his life and work, building a suspenseful gothic atmosphere.

Poe left a lot to the imagination, and so does A Midnight Visit. Initially, I look for some overarching story to the whole thing. I find a padlocked drawer, and wonder if there’s a key to it somewhere. I started out thinking of the show like an escape room, imagining that the different threads would cross over and build some mystery I had to solve. But after a while, I just let it wash over me. It’s exploration for the sake of exploration, with no real end goal.

With 12 hours of content unfolding within these walls, you can’t experience it all in a single hour-and-a-half visit. It’s a varied experience, with elements of horror, performance poetry, music and some intricate art direction. You’ll get lost, bump into people, crawl on your hands and knees and do all the things adults aren’t supposed to.

In an empty, run-down hospital ward I pull open a few drawers. Most are empty. To my delight, one is filled with candy. I take one. When I turn around, a very stern nurse in a Victorian-era uniform is glaring at me. I cower. She silently orders me to get into a rickety bed and tucks me in.

Suddenly I’m surrounded by other visitors in black facemasks, all staring down at me. The nurse explains to the assembled crowd that in this hospital, the ramblings of the insane are not only to be humoured, but encouraged. She pulls down my mask, takes a pipette from her pocket and administers two drops of liquid to my tongue. This is to be my diet for the next week, she explains. And just like that it’s over. The crowd disperses. I watch as other people find the drawer of lollies and, unfairly, receive no punishment.

“Particularly as adults, we stop getting to have fun and the engagement of being able to join the dots ourselves,” says Harvey. “We conceived this as something we would enjoy ourselves, to have that freedom to go in and play as adults.”

And Harvey and Siddle do enjoy it themselves. When I meet them at the bar after the show, both had to be dragged out of the performance. Even having designed the thing, it still has the capacity to surprise them.

“My favourite thing is to hang around while people come out, listening to them talk,” says Siddle. “They’ll have been separated, and they’ll have had very different experiences.”

“I think when people go their own way there’s a freedom in that,” Harvey adds. “And it’s great to come back together and compare notes.”

A Midnight Visit is at 222 Macaulay Road, North Melbourne until September 15.