'It's a big step up': Behind the scenes as Netflix hit Dept Q returns to Edinburgh

Walking onto any TV set is a thrill - and having followed Department Q since Jussi Adler Olsen's novels were first developed into a Netflix series, the chance to visit the sound stages of Edinburgh's FirstStage Studios was even more thrilling.

The second season began filming in the Scottish capital in June, and is due to continue until October.

I was given the chance to go behind the scenes and speak to some of those behind the success of Dept Q.

The set includes maverick detective Carl Morck's New Town flat. It's four times the size of any actual property so it can accommodate the cameras, lights and crew, as well as the characters who are supposed to live there.

The attention to detail is extraordinary, from the half full jars of jam on the kitchen surfaces to the takeaway menus and personal trainer ads on the side of the fridge.

Elsewhere, a steep flight of gloomily-lit stairs lead to the basement where Morck and his misfits are based – the abandoned shower quarter of the fictional police station which gives them the name Department Q.

There are showers, and some of the most disgusting-looking toilets I've seen since Trainspotting - perhaps a homage to Leith's other great cultural export. Everything looks as if the characters have simply stepped out for a moment.

The biggest set is the interior of the police headquarters – an open-plan office with personal effects on each of the desks and boards of photographs and details of the fictional cases they're working on.

Inside the office of Det Ch Supt Moira Jacobson (Kate Dickie) there are even more files, including the cold cases she passes to the team in the basement.

There's a bravery award in her name on the wall, and a peek in her diary reveals a series of appointments, meetings and to-do lists.

The concrete pillars and swirling sixties carpets look like they could be part of the brutalist Argyle House building in the city centre which doubles as the exterior of their headquarters – but they've all been built from scratch.

The only headache for executive producer Rob Bullock is that the actual building is now earmarked for demolition.

"I am very sad that I've had to sign up to very stringent anti-bribery rules through my employment at Sony, because otherwise I would be down there with a suitcase of money begging them not to demolish this building - because it IS department Q," he jokes.

The building's future is secure until at least 2033, when the current lease runs out – but with 10 books in the series, the production team isn't taking any chances.

They've already begun scanning the building in case a digital recreation is required.

It's all part of the framework which American showrunner Scott Frank started to build when he persuaded Netflix to locate the show in Scotland three years ago.

Although there were Danish versions of several Department Q books, he was keen to make the first big-budget English language version.

He was working on another Netflix show, the Queen's Gambit, in Berlin when discussions first began about possible UK locations.

Edinburgh - with its varied locations, crew base, and studio space – was already top of the list. Then he saw it in person.

"The first thing he said when he got off the bus on the Royal Mile was: 'I love this place, we're going to film here'," recalls Bullock.

Other commitments meant Frank could only direct the first few episodes, but this time round he'll direct them all.

"He has a real love of British detective shows like Cracker and Prime Suspect so he's always wanted to do his own version of that," says Bullock.

"And for all his many awards and achievements, he's never had a second season of a show so I think this was an opportunity to see what that felt like."

The new series is based on Disgrace, the second in the series of books about a group of privileged men in the top echelons of society who are involved in evil activities.

Bullock says the second series is "much more ambitious and much more cinematic".

"We had about 60 locations in the first season. In this one, we are well over 100, travelling all around Scotland.

"We are also doing these great big ambitious stunt set pieces. It's a big step up."

The central role of Carl Morck is once again played by Matthew Goode.

Is he as grumpy and as irascible as he was in the first season?

"I don't want to give too much away but Carl maintains his standard of being pretty grumpy," he says as we sit at the kitchen table in his flat.

"It's actually everyone else who starts falling apart in season two and Carl comes across as remarkably restrained."

He says the Scottish setting and cast allow for an added strand of dark humour.

"There's intended humour that came across a lot in season one and then there's stuff that comes from characters and situations and how we play together as actors," he says.

"There's a gallows humour that goes within the medium that allows us to be shocked and our coping mechanism as an audience, and in life, is to laugh at things.

"And that's what makes it slightly different from some of the Scandi stuff which can be ultra bleak. So go Scotland."

Leah Byrne, who plays DC Rose Dickson, says the show is "very unashamedly Scottish".

"That means a lot of light and a lot of humour, but also a lot of darkness, which I think Scotland represents very well," she says.

She's also delighted to return to her character's trademark vivid curls and brightly coloured outfits.

"It's an absolute joy to come back and get a chance to give Rose another go.

"I think she's got so much under the skin that we're only starting to scratch the surface of."

She's one of a number of Scottish actors returning this season.

The show has also given work to a wide range of technical staff, as well as training for 60 young people via a scheme funded by Screen Scotland, Sony and Left Bank Pictures, Rob Bullock's production company.

"We were keen to find people who wouldn't usually come into the industry and give them exposure," he says.

"It's not just about actors and writers; it's about carpenters and electricians. People think of the television industry as an exclusive world but it's an industry that encompasses a lot of different skill sets.

"What's great is when you see young people come in on a month training scheme and then be hired back in for daily work."

Although they're only halfway through filming for season two, and it won't be seen on screens until next year, most of Department Q's recruits are keen to keep on going.

And with eight more books in the series, they're hopeful this is just the start of this Tartan Noir tale.

"I think all of us feel the same - that it is an utter joy of a job to walk into," says Leah Byrne.

"It's felt so easy in a lot of ways. If we went for 10 series, I think all of us would be more than happy to stick around for it."