Outside Leith Theatre, Hidden Door artistic director David Martin sits in the sun, laptop perched on his knee and in deep discussion about technical matters.

Inside, this weekend will see Edinburgh’s grassroots multi-arts festival host the likes of Nadine Shah and The Orb’s Dr Alex Paterson on the increasingly high-profile venue’s main stage. For now, at least, however, the auditorium appears to have been overrun by a group of giant lizards, oversize swans and other creatures.

As more familiar human bodies flit in and out with purposeful intent, the monument-sized models cut quite a dash in the venue’s current state of flux. There’s a deck chair here, an upright piano there. The sound of large wooden panels being sawn in half permeates the air, intermittently accompanied by the machine gun rattle of an industrial drill.

Across the street, the bohemian-inclined Sketchy Beats cafe is open for business. In the old State Cinema that houses it, a generator hums with a hint of new life for a venue which is still partly used as a church. The building’s full expanse was last used several years ago as a nightclub called Babylon. While the likes of Emma Pollock, C Duncan and an already sold out show by Young Fathers will occupy Leith Theatre, the State Cinema’s labyrinthine and still largely dilapidated interior will become a second space for Hidden Door to house its theatre and dance programme.

Back over the road in Leith Theatre, a massive bullfrog perches beatifically on the stage, adding to the menagerie-like air of the venue’s increasingly jungle-friendly vibe.

“We got them from Edinburgh Zoo,” says Martin once his umpteenth meeting of the day has ended. “They seemed to fit with the jungle theme of our publicity, and after we spotted them, the Zoo very kindly let us have them.”

Such good will is typical of how Hidden Door works. The use of the State Cinema came about in a similar fashion, as Martin explains.

“We were really delighted how Leith Theatre worked out after last year, and wanted to come back and use it again, but we didn’t know how we were going to do that. There was a lot of chat about how Leith Theatre was coming back to life, but there’s still loads to do. In the end we felt that our job wasn’t done, so it made sense to come back and keep at it. Then when we were looking at other buildings, the nearest big building to Leith Theatre just happened to be this big derelict cinema, and we thought, we’ve just got to try and make it work.”

While Hidden Door’s previous negotiations concerning City of Edinburgh Council owned spaces have been somewhat protracted affairs, this was different.

“It was the most straightforward thing we’ve ever done,” says Martin. “The property developer who owns the State Cinema was really up for it, and didn’t need any persuading. Once we had that conversation, he gave us the key to the building straight away.”

The difference between Hidden Door’s two venues this year is striking.

“When you walk into Leith Theatre, it feels like it’s nearly ready to be a permanent venue again, and you want to see something being performed on that stage. When you walk into the State Cinema it’s much more derelict, and has a post-apocalyptic feel about it. It feels like an adventure. You don’t know what’s going to happen there. It’s got an edgy and almost scary feel to it, which we’re quite excited about and really want to bring to life.”

Hidden Door’s move into Leith Theatre caused civic leaders and other arts groups to sit up and take notice of the untapped potential of a venue which has lain empty and largely unloved for three decades. With it now under the management of Leith Theatre Trust. Edinburgh International Festival’s recently announced Light on the Shore programme of gigs at Leith Theatre, which includes a night curated by Hidden Door, look set to give the venue an international profile. It also sees Hidden Door help join the dots between different entities that make up Edinburgh’s cultural infrastructure.

“I think one of the big differences for us this year at Hidden Door is we’ve established partnerships with some of the bigger players in Edinburgh,” Martin says, referring to developing relationships with the likes of Edinburgh Jazz and Blues Festival, Edinburgh International Film Festival and Edinburgh Science Festival.

“What I think Hidden Door has which organisations like Edinburgh International Festival like is the way our audiences are really involved with what we do,” says Martin. “It’s a very engaged audience that we have. It’s not super high productions we do. It’s quite an intimate thing, and obviously with the cross-artform programming I think we get a lot of audience crossover. And of course,” he jokes, “the other festivals benefit hugely from our coolness.”

This year’s Hidden Door arrives at a time when Leith’s grassroots culture is in danger of being bulldozed out of existence. The block of shops on Stead’s Place, where thriving bar and music venue Leith Depot sits, has been bought by developers, with plans to demolish their purchase and build flats in its place.

It is noticeable too that LeithLate, which for the last few years has gathered assorted artistic tribes under one glorious umbrella of local grassroots activity, is taking a breather this year. ‘Save Leith Walk’ posters in shop windows highlight an already busy campaign designed to thwart the apparent destruction of local culture. As a nomadic enterprise, Hidden Door is in an interesting position.

“Our philosophy is that cities are quite fluid places,” says Martin. “We’re not into empire building, but we want to use the city to be creative, and I think we’re quite light on our feet. We want to support communities, and we want to invest in them, but at the same, Hidden Door isn’t a regularly funded organisation. We’re volunteer-run and have so few resources, so all we can do is make something happen. We can’t build an arts centre. That’s not our role.

“We see the city as something to respond to and move with, rather than try and plant our feet and say it shouldn’t change. The city will change. That’s what a city is. What we want is enlightened property developers who understand the benefit of things like Hidden Door, and work with them whilst they do the things they have to do to make the city work for them as well.”

Where Hidden Door ends up next year remains to be seen. The festival has never been held at the same venue more than two years running, and there are other spaces to unearth, with other doors to unlock. This time last year Martin expressed a desire to take Hidden Door outside Edinburgh. While that hasn’t happened yet, he still has ambitions to expand internationally as well as locally.

“We would love to take Hidden Door outside Edinburgh,” says Martin, “but that’s a question of our own personal resources. I’m disappointed we haven’t managed it this year, but I think having the extra venue is the only expansion we could handle this year.”

In the meantime, “We’re really excited about continuing to invest in Leith Theatre’s future, because it feels like it really has one now. There’s a lot more to be done, but it feels like there’s a will there.”

As for the future, “We’ve got our eye on a couple of places, and we’re having some complicated chats at the moment. Everything’s up in the air, but it always is, and that’s part of the excitement of Hidden Door.”

Hidden Door runs at Leith Theatre and the Former State Cinema, Edinburgh, May 25-June 3.