Credit: Dangerous Minds / BBC

I was about 18 and already considered myself a dyed-in-the-wool horror fan.

I was at my best friend’s flat along with their partner at the time, an older gentleman who had a good decade and a half of being a horror obsessive on the two of us. We were looking for something really shocking to watch, and their partner gave a small smile and said, “You want something really messed up?”

After a short Google search, he found exactly the film he was looking for. One hour and 40 minutes later, my best friend and I sat, ashen-faced as the credits rolled on a film that wasn’t scary in any of the ways that we were ready for. It wasn’t fun. It wasn’t thrilling. It wasn’t a brutally tense slasher flick like Halloween or an artful J-horror ghost story like Ringu. It was something quite unlike anything either of us had seen before, and at least for me, anything I’ve seen since, for good and for ill. That film was Threads.

On the surface, Threads seems like a strange movie to put in the pantheon of scariest films ever made. It’s a (relatively) small-budget TV movie made in 1984 by the BBC for about £400,000, chump change for a feature-length movie even then. There are no recognisable actors in it, let alone star names. There’s barely a score and not a hint of Hollywood gloss, making its settings of Sheffield and Buxton look like anything other than ordinary places in the Midlands. This makes the moment the bomb drops even more brutally terrifying.

Because that’s what Threads is about. It’s an examination of the medical, social, environmental and economic consequences of a nuclear attack on the UK with an almost documentary-esque level of realism. The film follows two families, the Kemps and the Becketts, in the days before and the years after a nuclear bomb is detonated over a nearby airbase, with the intention of showing one fact above all. A nuclear attack on the UK wouldn’t immediately slaughter the entire population of the country.

Just the lucky ones.

Why is Threads so shocking?

This is the heart of what makes Threads such a brutal watch. One would assume that the initial attack is the scary part, and to be sure, it’s a harrowing watch. The production team stretched their budget to the absolute limit to present a nuclear attack on Sheffield that is still genuinely immersive and doesn’t veer into anything you’d see on Doctor Who at the time. Threads makes it clear, however, that the actual detonation isn’t even the start of the problem.

No, Threads shows the societal panic a nuclear attack would throw us into long before the bombs drop. With anti-war protestors violently suppressed by the government, and full-scale rioting and looting in shops and city centres. Then the bombs go off, and then the real problems begin. Those that survive the initial strike are condemned to live, fittingly enough, a half-life. Society is barely hanging together, while the fallout mutates the next generation of humanity into something different.

Not in the rad Fallout way either, in the absolutely brutal way we see in the final scene. Where a character gives birth and is handed a bloody pile of rags. The shot freezes, and all we see is her horrified face as she looks into her arms. The last thing we hear in Threads is her agonised, petrified scream as we fade to black.

Among the things I’ll never forget about the night I watched it is my friend’s initial reaction to it. They were shaken to their very core and wondered why the film had to be brutal to the point of being exploitative. Their partner, who had watched the film when he was at school, reminded them that the film was made as such because at the time, the threat of nuclear war was a very real prospect. One that most people thought would be a nuisance that we could get through with good old-fashioned blitz spirit.

Threads had to cut through that. Threads had to show the country just how fucked it was if the worst really came to worst. That no amount of keeping calm and carrying on would get us through a nuclear winter. It’s a truly sad state of affairs that forty years after its release, Threads is still a horribly relevant watch.