For the most part, the trailer for the upcoming film One Night Only looks like the sweetest possible version of a romcom. A handsome, sensitive-looking man (played by Callum Turner) flirts relentlessly with a big-eyed oddball in a sexy dress (played by Monica Barbaro). They bump into each other, nudge each other, roll their eyes at each other. As a YouTube comment underneath the trailer (that has been liked more than 3,000 times) says: “Romantic comedies are back.”

However, tucked away in this adorable little trailer is a premise that might just be the most confusing in living memory. As Turner’s character walks lovelorn through the streets of New York City, his voiceover says: “Finding love is hard enough. Try doing it on the one night of the year single people are legally allowed to have sex.”

The trailer then hurries along to another procession of meet-cutes and prolonged eye contact. But that doesn’t really matter, because you’re left thinking: “Wait, the one night of the year where single people are legally allowed to have sex? What the hell?”

This, apparently, is the movie. Two cuties meet by chance, and are separated, and have to race across the city to find each other before the sun comes up so that they can enjoy a bout of government-mandated sexual intercourse. It’s a tale as old as time.

Clearly, this raises far more questions than it answers. Is One Night Only basically The Purge, but with all the terror of violence replaced by an increased risk of contracting chlamydia? More importantly, if there really is only one night a year where single people can have sex with impunity, how the hell is this even governed?

Judging by the state of the trailer, it seems to mean that everyone just claps eyes on someone and then starts banging them wherever they happen to be, whether that’s a restaurant or just in the street like a pair of horny rats. Why is this? Why don’t people just go back to their houses and then have sex? Does Sex Night also happen to fall upon a citywide taxi strike?

Also, how is this even enforced? Is there a government department that spends its days working out, with precise clarity, the point at which someone stops becoming single, and is therefore allowed to have as much sex as they want on any day of the year? Is it marriage? Is it the first time someone declares their love? If you wanted to be particularly Scandinavian about it, you might argue that sex itself is an act of union, and therefore any moment of penetration instantaneously suspends the notion of singledom. And if that’s the case, then surely everyone can just have sex whenever and there’s nothing illegal about it.

And what about all the unexpected pregnancies this will cause. Should there be a sequel set nine months to the day after One Night Only, full of people mournfully staring into the eyes of all the newborn infants whose sheer existence causes a permanent sense of regret to weigh down their souls? Will this even be addressed in One Night Only? Is anyone going to answer me?

Clearly this has to be a metaphor for something, but clearly the current level of evidence isn’t giving much away. Through one lens, you could suppose that it’s possible that One Night Only is a clever satire on the US right’s crackdown on reproductive rights, and the whole thing is an important and timely statement about the looming threat of a post-Roe worldview that may soon devour the country.

But at the same time, maybe this is about Covid? There’s something quite pandemicky about the notion that people would have to keep their primal urges at bay in a wholly unnatural way for an extended period of time. Remember how giddily we threw ourselves at each other once restrictions were lifted? Perhaps this is all just an allegory for that.

Or both. Or more. Maybe One Night Only is really about capitalism, or ChatGPT or the climate crisis. Maybe it’s none of them. Maybe it’s just the manifestation of a screenwriter who wished that, just once a year, people would be slightly more inclined to have sex with them. It’s honestly hard to say.

Nevertheless, if One Night Only is successful, then it’s bound to start an avalanche of “The Purge, but X” movies. What if there was only one night a year when you could have surgery? What if there was only one night a year where you could get a haircut? What if there was only one night a year where you could eat spaghetti with your bare hands? Because, if we’re already doing sex, then clearly there are no limits to the Purgiverse’s silliness.

• One Night Only is out in Australian cinemas on 6 August, US cinemas on 7 August and in the UK on 28 August