Louis Theroux on his experiences with addicts in the States for new hard-hitting series

He’s used to finding himself in tricky and unusual situations in his two decades of documentary making, but Louis Theroux’s latest US trilogy, Dark States, proved more challenging than ever.

Especially when, for this week’s opening episode Heroin Town, he filmed addicts in Huntington, West Virginia, who injected drugs in front of him.

“It was very odd,” confesses king of the understatement Louis, 47.

“It’s a documentary maker’s paradox. On one level you want to do the best job you can, so there’s an urge to think: ‘We need to see this in order to tell the truth about it.’

"But you’re conscious that it is distressing and obviously deeply harmful.

“In America generally, regarding heroin, it’s so out of hand. I was shocked at how many people were willing to shoot up on camera.

It’s been so normalised. It got to the point where I was trying to stop people from doing it if only to keep them present and articulate.”

One such person is self-proclaimed ‘heroin connoisseur’ Nate Walsh. Louis visits him in the tent he’s called home since becoming addicted to opiate prescription painkillers, then heroin, after being severely injured by a drunk driver.

“Nate is a friendly, intelligent and thoughtful guy who, when we first speak to him, you maybe even get the sense that he’s making his choice and his choice is valid,” says Louis.

“If he’s just out there in his tent, living by the river bank, shooting up and saying: ‘I love it,’ who am I to disagree? But then you delve a little deeper and find that there’s massive sadness and huge consequences with his 12-year-old son who he doesn’t see. It’s awful.”

Louis’ wide range of addict interviewees include Petty Betty, a woman who started taking painkillers from her parents’ medicine cabinet aged 12, and Edwin, a $200,000-a-year computer boffin.

But one of the most surprising interviews is with a woman called Katillia, who admits to resorting to robbery, stripping and prostitution to feed her habit – then alleges that her boyfriend Alvin, who she has just asked to leave the room, has been assaulting her.

“I had an inkling based on conversations my assistant producer had had with her,” admits Louis. “Her allegation was that Alvin could be physically abusive, but what I didn’t expect was for her to say it on camera. Then she suggested he’d more or less taken her hostage.

“Later she backed away from this [allegation] a bit, but clearly Alvin had been physical with her in a way that you can’t excuse. My take from that was that heroin relationships are, by their very nature, volatile and often abusive.”

The other films focus on the relationship between prostitutes and their pimps in Houston, Texas, and the very high murder rate in Milwaukee, Wisconsin, with Louis gaining no-holds-barred access to those he meets.

“The asset we have is that we’re a British team and we so clearly don’t belong there,” he explains. “We’re not seen as a threat. I think the accents help, funnily enough. You say ‘BBC’ and that we’re from London and it does go a long way to create goodwill.”

But is it hard for Louis to find much hope for humanity with all that he’s seen?

“I think I’m both an optimist and a realist,” he says. “I do see human nature as in some ways contradictory, self-sabotaging and weird.

"At the same time, what I get out of doing my documentaries is seeing that even in the darkest places you find resourcefulness, kindness, creativity and humour – and above all, human connections.

"So I felt privileged to be allowed into those worlds. Even though they were dark, I saw reasons for hope all the time.”

NEW! Louis Theroux: Dark States – Heroin Town Sunday 9pm BBC2

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