The depiction of a town ravaged by a heroin epidemic in Louis Theroux: Dark States (BBC Two) wasn’t exactly heart-warming Sunday-night viewing. Once upon a time you could rely on a Louis Theroux documentary to offer up a feast of ironic giggles at the foibles of humankind. But for years now he’s been going mostly to dark places, usually in America, with the sole purpose of showing us just how dark they are.

Here the location was Huntington, West Virginia, a rust-belt city that used to have a thriving steel industry but seems now to be in terminal decline. According to Theroux, one in four of the city’s 49,000 or so citizens is addicted to opiates of one kind or another. Huntington’s emergency services dealt with 11,000 overdose incidents last year, 13 times the US average. Horrifyingly, one in every 10 babies born in the city emerges from the womb already drug dependent.

Theroux toured the city, meeting addicts, watching them shooting up, getting them to say stuff about their chaotic lives that, given the familiarity of such stories on television, tended to sadden rather than shock. What was affecting were not so much the individual tales of addiction as the staggering scale of the problem, the incomprehensible extent of it.