When there's something strange in the neighbourhood, it's Ghostbusters you call – at least it is in Ivan Reitman's 1984 film about comedy ghouls on the loose in New York, and in Ray Parker Jr's accompanying theme song.

But if you're director Fabrice Gobert, creator of France's smash-hit supernatural series Les Revenants – and if the neighbourhood you've created is troubled by something stranger than ghosts – then you need something darker than slick 1980s pop to soundtrack it. So who you gonna call? Mogwai, of course.

"It wasn't hard," says Stuart Braithwaite, the Glasgow's band's guitarist, co-founder and general spokesman, when I ask him how he tackled the brief to score an off-beat French TV drama. "Being asked to make spooky music for dead French kids is the perfect remit for Mogwai."

After an acclaimed first season in France, Les Revenants comes to Channel 4 next month where it has been rebranded The Returned. Gloomy, atmospheric and chilling, it's based on the plot of a 2004 film of the same name and centres on a French mountain community to which some very strange things are about to happen.

It begins with a tragedy. As episode one opens, a bus carrying the town's teenage schoolchildren careers over a cliff. Months later, with the bereaved families still trying to come to terms with their loss and pick up their lives, some of the children reappear suddenly. They act as if nothing has happened (one heads straight for the fridge) and they try to resume their day-to-day existence as it was before the accident. Other dead people killed years previously – or murdered, in the case of one young boy – also reappear. Meanwhile, the town suffers mysterious power outages and the water level on a nearby dam starts to drop. Over all this, Mogwai's insistent, brooding soundtrack hovers like a pall of smoke. It makes for a pretty intense televisual experience.

"The people don't know they are dead," Gobert explains, "and they want to take their place back. Of course the living have moved on and the extraordinary reappearance of loved ones is both terrifying and wonderful. It's obviously a series about life, love and death, which are very universal themes. But what excited me most was to imagine how real people would have to deal with the extraordinary and how people who don't believe in God have no choice but to believe in miracles when they are presented with unquestionable physical proof."

It has been called a zombie series, but that doesn't quite catch its full-on David Lynch-style weirdness. That is where the music comes in. Gobert approached Mogwai because he is a fan of the band and in particular of the soundtrack they composed for Douglas Gordon and Philippe Parreno's French-financed 2006 film, Zidane: A 21st Century Portrait. "I've loved Mogwai for years and especially what they did for Zidane," he says. "I thought their music fitted perfectly with the atmosphere I imagined. I used to listen to Mogwai very often when I was writing the scripts."

Braithwaite, meanwhile, had seen Gobert's previous film, 2010's Simon Werner A Disparu, which was released in English as Lights Out and which featured a soundtrack composed by Sonic Youth. So something approaching a mutual appreciation society already existed between musicians and filmmaker. When they did agree to collaborate, the working methods were unusual, however.

"We had a summary of the story and a translation of the first two episodes and a lot of [visual] reference material – things like Twin Peaks and The Shining – and with that in mind we just went away and recorded a bunch of demos," says Braithwaite. "We sent them on and they said which ones they liked. They played a lot of them while they were filming so they were actually feeding off the music while they were making the show. It was quite a symbiotic process."

As production began, the band were sent still shots so they could build an idea of the characters. Later they saw some footage. But by this point the music they had already supplied was being used in rehearsals to guide the actors, among them Frederic Pierrot, who starred in the original 2004 film.

So did Braithwaite ever imagine the series would end up being shown in the UK? "Because there has been a vogue for foreign-language TV, I did think it might, but I suspected it would be on a satellite channel at three in the morning. So I was really happy when I heard it was going to be Channel 4."

For Gobert, the music is a character in its own right. Or, more specifically, "a narrator" which adds "mystery, a sense of fear or melancholy" to the scenes. "I certainly didn't want an obvious score which underlines the feelings of the characters, or which explains situations and tells viewers what they should be feeling," he adds. "Above all I wanted them to feel free and not to try to copy the classical thriller scores."

To that end the only musical steers he gave Mogwai were Neil Young's minimal, plaintive soundtrack for Jim Jarmusch's 1995 western Dead Man, and Miles Davis's equally plaintive trumpet score for Louis Malle's 1958 classic, Lift To The Scaffold. Neither film could be described as a zombie flick.

The only other visual pointer besides Twin Peaks and The Shining was the work of Gregory Crewdson, an American photographer who blends the mundane and the surreal into something deeply sinister. Gobert also mentioned writers such as Bret Easton Ellis, Edgar Allan Poe and Mark Z Danielewski, author of cult horror novel House Of Leaves.

"We enjoyed being hired hands and adding something of ourselves to someone else's vision," says Braithwaite. "Zidane was certainly a reference point for this, but the project itself was 100% different. Douglas and Philippe really just gave us a free rein on that, whereas with Les Revenants there's a framework, you have to build tension and help tell the story through the music. Zidane was completely open."

It wasn't all plain sailing though. "Most musicians who have worked with film or TV have amusing stories about how they're asked to do things in terms which aren't applicable or which aren't understandable," he adds. "So that, added to the language barrier, did throw up some amusing email exchanges – things like: 'Can the music be more hesitantly powerful?' What the f*** does that mean?"

It's notable that both of Mogwai's soundtrack contributions so far have had their genesis in France. Braithwaite's bandmate Barry Burns was involved with the soundtrack for David Mackenzie's 2003 film Young Adam – and Mackenzie is currently recording sound in Mogwai's Glasgow studio with producer Tony Doogan – but it hasn't escaped Braithwaite's attention that offers to work with Scottish filmmakers have been thin on the ground.

"If it's going to happen this will certainly show that we can do it. And sometimes people do take a left-field decision on who they're going to get to make their music – sometimes it doesn't work, but sometimes it does and wonderfully too. I would love to work with some of the people making good films here.

"When you see some of the amazing things Peter Mullan does, it would be wonderful to be involved in something like that."

One offer that did come in and which he regrets turning down was from Nicolas Winding Refn, the Danish director of the acclaimed Drive and Only God Forgives, currently showing in competition at the Cannes Film Festival. Winding Refn wanted Mogwai to score his 2009 Viking-era film Valhalla Rising, which was shot in Scotland and starred Mads Mikkelsen. In the end the director turned to Peter Kyed, who had scored his Pusher series of films.

"It was a scheduling thing," says Braithwaite of the reasons the band couldn't commit to the film. "He really made a lot of effort to ask us and, having seen some of the things he's done since, I do regret not making time for him."

Perhaps the Vikings' loss is the zombies' gain.

The Returned starts on Channel 4 next month. Mogwai's soundtrack album, Les Revenants, is out now on Rock Action.