Connubial duo The Handsome Family have been dissecting the American heart of darkness for the past 20 years, setting blackly humorous yarns spun by wife Rennie Sparks, and sung mainly by husband Brett against an engaging gothic folk backdrop. So their haunting Tex-Mex track ‘Far From Any Road’ was the perfect choice of theme tune for the first series of True Detective, set in the Deep South and dripping in creepy atmosphere.

Yet despite recently appearing on Reginald D Hunter’s excellent travelogue TV series Songs Of The South extolling the vices of southern gothic, the couple are reluctant to bag that description for their own music. Rennie points out she isn’t even from the south, hailing originally from Long Island before forming the Handsome Family in Chicago and then moving on to their current base in Albuquerque, New Mexico.

‘I think we’re just writing about America,’ she says. But what an intriguing perspective on America compared with, say, the cheerleader jingles of Taylor Swift. You don’t get songs ostensibly about fish, fowl, reptiles and creepy-crawlies but actually about 19th century vandalism sprees or the unfortunate death of the man who wrote ‘Swanee River’ from Foo Fighters. But you do on the current Handsome Family album Wilderness. ‘The octopus has three hearts and can think with its arms – that deserves a song!’ reckons Rennie.

This is folk music in all its outlandish, fabulist glory. ‘I love the old stories,’ says Rennie. ‘I think of old folk songs as a time machine back to earlier human dreams and consciousness. I also think that folk songs are the only place where Christianity didn’t manage to wipe out all traces of older religions. Old Scottish folk songs have a lot of pagan references to flowers and trees and mountains and blood.’

But Rennie is also drawn to contemporary local traditions and superstitions. ‘Sage burning is very popular here,’ she says. ‘There are natives selling little bundles of sage and juniper on street corners in the summer. You burn it in all the corners of the house to get rid of demons. We also paint our window and doorframes turquoise to scare away the chupacabra [fabled ‘goat sucker’ of Central and South America]. I am glad to live somewhere where rational thought isn’t king. Rational thought is far overrated in my book. I fear we lost something precious when alchemy turned to chemistry and left the spirits behind.’

The Handsome Family do such an evocative job of projecting a skewed, slightly fantastical worldview that one wonders what constitutes regular home life for the couple. Brett has mischievously claimed that ‘there are three people in our marriage – there’s the two of us and the Devil. Or maybe it’s the Lord’, while Rennie makes an inspired, unwitting pitch for an ‘at home with the Handsome Family’-style reality TV series.

‘Mostly we sit in our pajamas in the living room and listen to Bach in the dark. We have two cats and follow their warfare with the neighboring cats vicariously. I often don’t comb my hair for weeks at a time. It’s a good life. And then inevitably we have to pack up and tour to make some money. Ah, the dread of the suitcase.’

The Handsome Family play The Tolbooth, Stirling, Mon 9 Mar; Pleasance Theatre, Edinburgh, Tue 10 Mar; St Andrews in the Square, Glasgow, Wed 11 Mar.

The Handsome Family – Far From Any Road (True Detective)