FRIENDSHIP means a lot to Stef Smith, whose new play, Enough, forms part of the Traverse Theatre’s Edinburgh Festival Fringe programme when it opens next week. More significantly, perhaps, following her recent radical reworking of Ibsen’s play, A Doll’s House, it is female friendship that the Stirlingshire-born writer is focused on. That, and aeroplane cabin crew, who probably aren’t quite as jet-setty as advertised.

“I’ve always been fascinated by air stewards, both male and female,” says Smith. “I think it’s such an interesting performative role. I’ve always found it fascinating when you see them doing the drinks trolley or showing where the emergency exits are, and in the middle of the flight you’d go up the back, and you see them all hanging out, and they’re all really relaxed and talking about what they’re going to have for lunch. It’s quite a different energy, and also very theatrical.”

Smith's play focuses on two female best friends who spend half their lives up in the air.

“It’s about what it means to be a modern woman in a role which in some ways hasn’t progressed with the times,” Smith says. “It’s a role that looks after your lunch and your life at the same time.”

Did Smith speak to any real life cabin crew as part of her researches? “Not directly,” she says. “I spoke to a couple of pilots, and again it was fascinating. It’s such an interesting industry, and is so variable depending on the airline you work for. Years and years ago I did speak to some cabin crew, because it feels like it’s been in my veins to write about cabin crew for about ten years. There’s loads of blogs on YouTube by young women who’ve trained to be air stewards talking about what it’s actually like to do the job rather than what it's seen to be, and the sheer in-the-trenches nature of the job.”

These days, working as cabin crew perhaps doesn’t have the cache it once did.

“It was glamorous,” she says, “and it was the only way to travel. Until budget airlines kicked off, for lots of women who didn’t have much money it was a way of getting a lifestyle you couldn’t otherwise have. Now, it’s very different. It’s a role that’s stayed the same, but the world around it’s changed.

“I also really wanted to write a play about friendship, because I think it’s quite a neglected subject matter in plays. There are plays about families or romantic relationships, but there isn’t a host of work solely platonic friendship, and particularly long-standing friendships or female friendships. I don’t feel I’ve seen many plays within that Venn diagram, and my female friendships have been so important in my life, so it was definitely territory I wanted to look at.”

With the two women in the play played by Louise Ludgate and Amanda Wright, Enough isn’t just a gal pal play.

“In the first part, the women start to feel these tremors beneath them,” is all Smith can give away. “That causes things around them to fundamentally start to shift, both physically and psychologically, and they go on a journey that reveals who they are to themselves and the world they exist in. It flirts with magical realism, and as the play goes on you start to question what’s real and what’s actually happening to them, and how you deal with a world that’s fundamentally changing, and how you don’t know where your place is within it.”

Enough started out as a more explicit expose of male power. After a couple of years on the back-burner, however, “what had felt a bit zeitgeisty now seemed parasitic.”

Smith threw away what she’d written, taking the characters into a new orbit.

“I’m not a big fan of theatre that tells you what you should do,” she says. “I always aim to give space for under-represented voices, and I think the universal is always in the specific, and so, although obviously Enough is about female friendship, I definitely want men to be able to sit there and feel like a part of them is being explored, or that they see their sisters or their mothers in the people onstage.”

Despite this, Smith recognises that Enough arrives at an unmistakably volatile time.

“I’d like everyone to see that it’s an exploration of humanity at this very particular and extraordinary point of history that we’re in,” she says, “where all the rules are changing all of the time, when we’re constantly being told how unsafe everything is. That’s a lot for our little animal brains to take in, and we’re not designed to cope with that level of knowledge. That’s why people drink and take drugs, and that’s something that’s explored within the play.”

In this respect, Smith’s characters are far from perfect.

“They’re naughty and messy,” she says. “My note to the actors is that the audience should want to get drunk with these women, because they’re fun and cheeky, and they’re tough. They’re strong women, and aren’t victims, but that doesn’t mean they’re invincible. What Louise and Amanda are doing so beautifully is inhabiting all that complexity about what it means to be strong and fragile and modern, but also have desires that are maybe more traditional.”

There is a personal drive too that courses through all of Smith’s work.

“With everything I write,” she says, “I want to give back as a gift what theatre has done for me, which is to feel less alone in what you feel and think. I would love the audience to sit there and feel that, and that it’s possible to live and survive and continue, and then have a really good time.”

Enough, Edinburgh Festival Fringe @ Traverse Theatre, Edinburgh, previews July 27and August 1, then August 2-25, various times.