YOU will realise the moment you enter Tramway how this show got its name.
That's only the start of the fun. The reason Laing wanted the audience to be at a high level is so they could watch the show from above. He wanted to create the ultimate in theatrical voyeurism: a group of spectators staring down at someone in a bathroom.
"I'd been looking at Degas' drawings and Nan Goldin photographs," he says. "There's an intimacy in those images that, working in the theatre, you feel excluded from, as if somehow it's not an area open to you. I wanted to be able to look at people that intimately in their bathroom in the work that I do. Why is Nan Goldin allowed to do it and I'm not?"
Laing's first experiences in the theatre were "driven by voyeurism" and he acknowledges that one of the medium's least trumpeted attributes is the opportunity to ogle. "I stare at people," he says. "That's socially unacceptable, but the theatre gives you a licence to stare. And looking down at someone seems even more voyeuristic."
He could, of course, have built his bathroom in a box and put stairs on the outside, but he was unwilling to make things awkward for anyone with a physical disability. He toyed with ramps at angles, but nothing was as elegant - and as inclusive - as the remarkable slope he has come up with.
"We were going to do it in Tramway 4 and we started working out disabled ramps, but they were ugly because of the gradient you needed," says Laing, whose work beyond Glasgow has included designs for Titanic on Broadway, the Wooster Group, the Builders' Association and the National Theatre of Scotland's inaugural Home project in Stornoway. "The visual arts space was the one place where we could have one clean ramp. It means there's a slight incline from the street to the bathroom and it's a really clean image."
If it seems odd to talk about the design of a show before mentioning what it's about, that reflects the working methods of Laing and his company, Untitled Projects. His bathroom idea came first, then the notion of doing something about the relationship between Arthur Rimbaud, the precocious 19th-century French poet, and his sometime lover Paul Verlaine. With these thoughts in mind he approached Pamela Carter to see if she would write him a play.
"There are probably a lot of playwrights who start off with an image," says Laing. "Oddly enough, the picture I had in my head is not in the play. Pamela didn't write it. Theatre is a collaborative artform and the best theatre comes out of collaborations."
The script Carter produced - her first solo play - was another surprise. The former research associate at Suspect Culture and director of her own company, Ek, is known for her leftfield experiments and Laing assumed she would turn out something open-ended and fragmented. In fact, she surprised even herself by producing a three-act love story that, were it not being performed in a bathroom, might even be called traditional.
"I think I've written a very conventional play," says Carter, whose Game Theory, co-written with Selma Dimitrijevic, will be seen at Glasgow's Tron in the autumn.
"The work I've seen of Pamela's has veered towards performance art," says Laing. "We were all expecting cut-up images interspersed with French poetry. That's absolutely not what she did. It's a three-act play with three characters who all have an emotional arc. It's such an unconventional story that you don't want to be sitting there piecing it together. It means you focus on their unconventional love affair rather than the form in which it's being told."
Carter felt liberated by the specifics of the director's brief: her only modification was to introduce a new bathroom for each act, taking us from a bourgeois bathroom in Paris to a dingy bathroom in a London garret and a communal hotel bathroom in Brussels. Here she tells the story of the teenage Rimbaud, the brilliant, heavy-drinking iconoclast, and his turbulent relationship with Verlaine, 10 years his senior and already married to Mathilde Maut.
"The first bathroom is a very clandestine space, the second is domestic, where they're living together, and the third is where they're homeless and everything falls apart," she says.
Tweaking some of the historical facts and introducing anachronisms of language, Carter explores the nature of addiction and desire, and asks why chaos and creativity so often go hand in hand. "Rimbaud and Verlaine raise issues of taboos," she says. "They had an obsession with dirt. It was a fairly scatological relationship. The word 'obscene' literally means 'off stage'. So we've got the obscene on stage."
Rather than be offended by this material, Laing and Carter find it funny, regarding the play as a "bathroom farce".
"When you read the events of their life, they are farcical," says Laing. "Rimbaud revelled in pushing things - like the dramatic situations - as far as they could go. Pamela's play is a frank look at the relationship. It's not glamorised in any way."
• Slope, Tramway, Glasgow, July 15-29