After months of fevered expectation the Tardis materialises in Ipswich this weekend to investigate the mysterious Crash of the Elysium.

It’s a huge set-piece of 21st century theatre in which the audience is also part of the cast.

This is immersive theatre, active theatre: a trademark of co-producers Punchdrunk Theatre company. It’s an adventure which has been forged by Dr Who script writer Tom MacRae from an idea by Dr Who supremo Steven Moffat.

The show puts audiences at the heart of the action by staging the show inside an enclosed set which has been constructed on Crown Street car park.

Like some hapless victims in a real-life Dr Who adventure, our only way out is to play the game. The play The Crash of the Elysium is a co-production between the New Wolsey Theatre, Punchdrunk, The Arts Council and Ipswich Borough Council to help the nation mark the Cultural Olympiad.

It’s been directed by Punchdrunk founder Felix Barratt, who has pioneered immersive theatre in both the UK and the USA.

Ever since he was a drama student at Exeter University he has been creating site-specific theatre which not only engages the audience but also makes the audience part of the action. It doesn’t happen without them.

Two of the actors involved in the show, Kat McGarr and Matt Odell, are hugely excited about the prospect of running the show with a real audience, as this will give them new cast members to scream alongside.

Both are veterans of the pilot show which was trialled in Manchester last year and are hugely enthusiastic about the show which is about to be unleashed. They happily chat away about what exhausting fun the show is but, as we talk, the problem of what they can and cannot say keeps cropping up.

It turns out that both actors are playing the same role on different shifts, but they can’t tell me the name of the character they play.

“The problem is, if we tell you who we are, then it will give away some details about the show,” explains Kat.

An earlier chat with scriptwriter Tom MacRae has revealed the bare bones of the story. Tom says that the play works best if the audience knows next to nothing about what is about to happen.

He said it is safe to reveal that the adventure involves a wrecked steamship, The Elysium, which sank in 1888.

The audience are invited to an exhibition about the wreck, discover a crashed spaceship, and then there’s running and screaming.

The show is designed to work for all ages. There will be family performances for both adults and youngsters, schools’ performances for just children and an adults-only version where, according to Tom MacRae, the stakes are raised higher, the tension is ramped up and it’s much more terrifying.

He said the key to getting the audience to believe in the show was maintaining an extraordinary attention to detail. Everything had to be believable. Once inside the set, nothing from the real world can be allowed to intrude.

“The Crash of the Elysium only works if the people in the show believe that everything around them is real and they are helping the Doctor fight for their lives.

“We create a world which they enter. It’s not like going into a theatre, sitting down and enjoying the show – it’s more like your real life becomes the show.”

Tom said that writing the play was an exacting task because not only does it have to work as a play, it also needs to function as a three-dimensional experience which thrills, entertains and scares in equal measure.

“Dr Who has always been about hiding behind the sofa and peeking out, but now there is no sofa to hide behind.”

This chimes with Kat and Matt’s view. They believe the show works only if the audience is scared and if they play an active role in the performance.

Kat said: “As regards to the narrative, the audience are key. They are the narrative. We facilitate it, we hit the right points in the music, we deliver the right cues, but our role is to really keep the action moving.”

She said that the key to the performance was the feeling that people got from being thrown together in an enclosed space and being thrust into a situation where they didn’t feel in control. “It’s like walking onto a film set mid-shoot and you have to discover the world as you go along. You are swept up in events which have already been set in motion. But you can shape them as they go along. You are completely thrown into the plot and you have got to run with it – quite literally.”

Matt added that based on the way audiences reacted last year in Manchester, it won’t take long for people to seek support from one another.

“It’s interesting because very quickly audiences start to bond and work together. There are moments in the show where you are scared and want to get out but if you stick with it and get to the other side you have this tremendous feeling of elation.”

Kat said: “I was talking to one woman at the pilot show and she said that at one point she just grabbed the nearest arm to her – she didn’t know who it belonged to – and just hung on.” They said their greatest thrill is to see audiences as they emerge from their trip to an alternate universe. “It’s interesting to see audiences after the show because they are just buzzing. They are laughing and jumping around. The adrenaline is still pumping and they are just relieved to have got through to the other side,” said Matt. “You get this visceral feeling that you are incredibly alive. It’s much like the feeling you get on a rollercoaster ride. You get that same feeling of release. Audiences have this feeling that they were part of something and ‘we all did it together’.”

For Kat, Matt and the other actors, they love the edge-of-the-seat nature of the performances. They said that because not everything is totally scripted there is a sense of danger and excitement which keeps everyone on their toes.

Matt likened the experience to walking into a rehearsal two minutes before curtain up on opening night and being told that they have to put on a play.

“It’s crazy but huge fun.”

Kat said that although there is a lot of room for audience interaction, the basics of the show have been locked in place by Tom MacRae.

“There is a set narrative and it can only unfold one way. We do have lines but we really only have a skeleton of a show. There are cues and there is text and there is narrative that we have to get across, but away from that you have got the freedom to interact with your audience.”

Matt said that the show changes with every audience; their reactions are different, and so, as actors, they have to keep on their toes.

He said that the atmosphere of working in an enclosed space really did help set the scene – aided by dramatic low-level lighting and alarming sound effects.

“You are completely surrounded by a fully-realised world. You can touch things, you can pick up props and before you know it you regard them as real. Props become tools you can use.

“It is very easy to forget you are in a play; hopefully you will be transported to another place where you have to run for your life.”

He said that it is interesting to see that both young audiences and adults both engage with the show on the same basic level. It doesn’t matter if you are five or 85: fear and suspense provide the necessary adrenaline for a wonderful experience. “It’s rather like walking into a haunted house. You can’t shut your eyes and hope it will go away, because it won’t. It’ll still be there and you have to engage with it. You have to provide some action. You can run away but you have to do something to change the scene and move the story forward.”

Kat said she loves working with audiences that are just living in the moment and experiencing the show as it unfolds. “That’s why it’s good not knowing too much about it before you come – everything’s a surprise.

“It captures exactly what Dr Who is all about. They are all in that head space. I don’t know of any adult audience who didn’t enter into it. I love the fact that they just get caught up in it all.

Matt added: “The whole thing is based on the notion that everyone who walks in would quite like a cushion to hold over their face. Just like when you see it on the telly. It’s up and down all the time and Crash of the Elysium is just like that.”

He said that at times it resembles a 21st century Ghost Train ride. “Felix loves his terror rides and fairground experiences, so that’s a pretty accurate analogy.”

As rehearsals are coming to a close they are pleased to report that after the try-out shows in Manchester last year the show has been tweaked and changed and is tighter and more focussed, and should give audiences plenty of opportunities to scream and run through this amazing world which has been constructed especially for the play.

The other piece of good news is that both The Doctor – Matt Smith – and the series head writer and producer, Steven Moffat, have seen The Crash of the Elysium and have given it their seal of approval.

Kat agrees that it’s important to have the backing of the keepers of the Dr Who flame.

“At its heart it is an absolute Dr Who experience because it gives you that same feeling you get when you watch it.” Matt adds: “It’s a fun adventure; it has bits which are quite funny, then it’s ‘oh dear, that’s quite scary. I think I’m going to hide behind the sofa now.’ That feeling is intrinsically part of the Dr Who set-up. I remember having nightmares about Davros. I think each generation have their own terror moments that stay with them.

“I hope that for a whole generation of kids, having an adventure with The Crash of the Elysium will provide one of the defining memories of their childhood.

“Certainly I have adult friends who saw the show in Manchester and they still talk to me about it, but for kids – if you see it at a certain age – then it stays with you for life.”

So as we finish our conversation, can they give any clue as to their collective character? Have they put their heads together to come up with some defining characteristics?

The pair look at each other quizzically. Kat asks Matt: “Who are we? I see myself as Ripley out of Alien – Sigourney Weaver. How do you see our character?”

Matt looks a bit sheepish: “It’s going to seem an odd answer but I feel like the dude in Predator, who wears the glasses and gets hit in the chest by the log. He’s a bit of a nerd – he’s an enthusiastic geek.”

So, change is obviously a constant and there is plenty of room for audiences to shape the story as they go along.

n Dr Who: The Crash of the Elysium is at the Crown Street car park in Ipswich until July 8.

Tickets must be pre-booked via the New Wolsey Theatre.