Image caption Jane Leaney as Dolores Grey in The Drowned Man

Punchdrunk's largest ever project The Drowned Man - which opened in London this week - allows its audience to explore the seedy underworld of a Hollywood film studio. Where can "immersive theatre" go after this?

In a vast former sorting office next door to Paddington Station, Punchdrunk has created a sprawling, surreal world for its latest show The Drowned Man: A Hollywood Fable.

Over four floors there are gloomy corridors, bedsits, shops, bars, trees, caravans, chapels, even a working cinema.

They can almost feel the breath of the performers on them. Felix Barrett

Since 2000, the theatre group's speciality has been to transform entire buildings into mysterious locations which audiences explore as the action unfolds around them.

The Drowned Man, a co-production with the National Theatre, is the company's most ambitious work to date.

"It's the first time we've played with the idea of more than one lead narrative," explains Felix Barrett, Punchdrunk's artistic director.

"There are two versions of the core story playing out simultaneously. There are far more hidden secrets to discover."

Previous Punchdrunk shows include The Masque of the Red Death, at the Battersea Arts Centre in 2007, and Doctor Who spin-off The Crash of the Elysium, originally a hit at the Manchester International Festival in 2011.

The Drowned Man - reviewed "It's hard to legislate about a show where everyone will have a different experience," said The Guardian's Michael Billington. "For me, the best moments were often the smallest." "For all the thrashing around of Maxine Doyle's DV8-style choreography and for all the extraordinary logistical flair of the staging," said Paul Taylor in The Independent, "the dramatic encounters come across as signalled rather than experienced and the show, which ends in a company hoe-down, as over-stretched and lacking in heart." The Drowning Man "resembles both a vivid dream and a startling LSD trip", said Charles Spencer in his five-star review in the Daily Telegraph. "As you explore this murky, maze-like venue, you often find yourself completely alone, nervously opening doors to discover fresh wonders and new horrors... this is surely a huge cult hit in the making that will be talked about for years to come." Time Out's Andrzej Lukowski was less impressed. "As Punchdrunk's shows grow to such a vast size that any meaningful opportunity for the casual punter to work out what the hell is going on flies out of the window, I experience the peculiar sensation of being simultaneously overawed and a bit dissatisfied." The Guardian The Independent Daily Telegraph Time Out

The company's current New York show Sleep No More, which opened in 2011, is a twist on Macbeth.

Punchdrunk's return to London sees the creation of Temple Studios in W2 - described as the British outpost for major Hollywood studio, Republic Pictures.

Audience members - who must wear masks - are free to explore the film sets and the world beyond the studio gates.

A tragic love story - inspired by Georg Buchner's unfinished play Woyzeck - is played out by a large cast of actors and dancers. Some scenes take place in tiny spaces, where only one or two people are watching.

The idea is that everyone's experience will be unique. "We're trying to remove the audience from their comfort zone and lose them in a parallel universe," admits Barrett.

As they move around The Drowned Man's 1960s film studio setting, the audience members are effectively piecing together their own movie. But it won't necessarily make any sense.

"The audience is the camera floating around this dream," says Barrett. "All we are doing is presenting loads of content like the unedited rushes for them to cut together."

The mask, he adds, is the "fourth wall" that enables the audience to become anonymous and get closer to the action. "They can almost feel the breath of the performers on them. The mask enables them to become the camera."

Seeing the show earlier this week, it was an odd experience to watch the characters walk, fight, sing, dance - even undress - as if you were invisible.

Image caption Sophie Bortolussi as Wendy in The Drowned Man

Theo Bosanquet, editor of Whatsonstage.com, points out that "immersive theatre" has come on leaps and bounds in the last decade or so.

"Punchdrunk were by no means the first but they took the genre to a whole other level, and The Drowned Man marks the culmination of that."

Recent examples of immersive theatre include the award-winning You Me Bum Bum Train and Dreamthinkspeak's In The Beginning Was The End - a site-specific show in the underground vaults beneath London's Somerset House.

Even as Punchdrunk becomes "a huge international brand", Bosanquet predicts that immersive theatre has a lot more to offer.

"The possibilities for the genre are endless. There's a computer game-like experience offered by immersive theatre that really appeals to a younger generation," he notes.

"What's interesting is the way immersive theatre can turn small audience numbers to its advantage - the thinking being that if you've only got 10 people seeing your show you may as well give each one of them a unique experience they'll never forget.

"For that reason I think fringe and avant-garde companies are going to be using immersive techniques more and more, as a way of standing out from the mainstream.

"I think it will become the medium of choice for new companies. It has by no means had its day."

Media playback is unsupported on your device Media caption Punchdrunk Theatre has taken six years to find the right venue

Punchdrunk's Barrett admits that he's not a fan of the term "immersive theatre".

"We would never use it ourselves, although I'm delighted if our audiences are totally immersed," he says. "We used to call it 'site sympathetic' - because it's all about the building."

In what direction does he want to take Punchdrunk after The Drowned Man?

"We've got a three projects in development that are very different to this. I'm excited to see what happens if you take the work outside of the building on the streets."

So no plans to inhabit an even bigger space? "No, it's about giving the audience something they are not expecting, it's about pulling the rug from underneath them."

The Drowned Man is at Temple Studio, Paddington, London W2, booking until 30 December.