If you were looking to name the most talked-about programme on TV right now, you wouldn't have to be an obsessive policeman with a deductive intuition to alight on True Detective. Praise has been lavished on Woody Harrelson and Matthew McConaughey in their roles as Louisiana state detectives Marty Hart and Rust Cohle. The mystery, in which the pair investigate a ritual murder in the bleak wilds of the bayou, has prompted much speculation and theorising. Some of us have even admired the folk crafts (wherever the detectives go they stumble over piles of spooky wooden icons). What binds the serial together, though, and elevates True Detective into truly compelling television is its eerie tone and complex structure. And that achievement is the work of 36-year-old director Cary Fukunaga.

"One of the images I first saw in my head when I read the screenplay was a plain landscape towards dusk," says Fukunaga over the phone from his home in New York. "There was a still, Magritte-like light hanging in the sky and these two cold, hard characters at the front, staring at a burned-out church. I loved the starkness of that, the openness of everything being exposed to the air. There's a lot of two-hander dialogue in True Detective, and I needed to place those guys in locations where there were other levels of visual storytelling. It didn't necessarily have to move the plot forward, but it had to add tone or add to the overall feeling."

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That feeling is where much of the tension of the drama is derived; the broad, silent spaces of rural Louisiana are both beautiful and somehow menacing, as if the land itself is holding secrets. Fukunaga's keen attention to his craft is reflective of a career that has begun at lightning pace. As with the stars of his drama, Fukunaga comes from a feature-film background. Born in Oakland, California, to Swedish and Japanese parents, he studied film at New York University. His debut, migrant drama Sin Nombre, won both best cinematography and direction at the Sundance festival in 2009. To research that project, Fukunaga joined real migrants as they travelled across Mexico on the roofs of trains, exposed both to the elements and criminal activity ("We were attacked by gangsters within three hours on my first night," he has said). Two years later, Fukunaga delivered something very different: an adaptation of Jane Eyre with A-list Hollywood leads in Mia Wasikowska and Michael Fassbender.

While big-name actors appearing on the small screen have become a familiar sight in recent years, it's less common for a director to make the switch. The demands of the role are very different.

"If you're directing," says Fukunaga, "it doesn't really matter any more if it's going straight to TV – what matters is whether you have the resources to make a story that moves you. The latter comes first. Increasingly, there's much better material on television, but there's not always the time and money to make it, so you've got to make sure you make it in the right place. It also depends on time commitment; a lot of directors will make a pilot but a series is just a whole other level of involvement.

"I remember one of my tutors at NYU telling me that making a feature film is not like making six short films but a whole different endeavour. The same applies to making eight hours of TV. It wasn't going to be like making four features, it was going to be a whole different way of looking at narrative art."

This applied not only to the structure of the drama – which jumps between the years 1995 and 2012 – but in its actual filming. The final four episodes had to be planned at the same time as the first four were shot. The crew ended up working "six or seven days a week for six months".

Into this mix came the star duo of Harrelson and McConaughey, the latter fresh from his soon-to-be Oscar-winning performance in Dallas Buyers Club. "The first conversation I had with Matthew on the phone, I could tell he was a smart guy. The first time we met he brought some music that he thought would work for the show. Initially we had differences in how we envisioned Cohle, but in terms of where he came from, we 100% agreed on that. It was up to Matthew to put the flesh on that, be it in his voice or the way he moves. I wasn't quite sure what he was going to do but I was very pleased with the results.

Woody Harrelson and Matthew McConaughey in True Detective,

"I remember on the first day of shooting being struck by the way he smoked a cigarette," Fukunaga continues. "We weren't sure how much he was going to smoke yet, but I had made some comment early on – because he doesn't smoke and is very healthy – where I said, 'Just make sure you don't smoke it like a high-school girl.' He must have taken that as a challenge because by the first day of filming he was smoking a cigarette like it was a joint."

After saying this, Fukunaga takes a moment to correct himself; he didn't mean "high-school girl", more like "don't look like you're faking it". This revision seems a little self-conscious and perhaps belies an awareness of the other discussion that has centred around True Detective: its shortage of well-drawn female characters. New Yorker critic Emily Nussbaum wrote of the show, "It was about the evil of men who treat women as lurid props, but the show treated women as lurid props."

"Look, the story is what the story is," says Fukunaga when I ask him about the criticism. "It's about two men who work in a very macho industry, in terms of the area they're working in and the crimes they're dealing with. But it's about two men's dysfunction as much as anything. The show is not going to pass the Bechdel test. I considerably doubt that. So is it sexist? I don't know. I always focus more on the main characters and what they're doing, and I didn't write it, so… My job is to make the best version of that story possible."

Next up for Fukunaga is a return to the big screen, a "small, simple" film about a child soldier in west Africa, with Idris Elba playing the leader of a rebel battalion. Are his friends at all envious of his prodigious career? "My friends just make fun of me in some shape or form. I got lucky."

True Detective is on in the UK on Saturdays, 9pm, Sky Atlantic