Human beings tend to have a strange fascination with tragedy. Everyone has a “where I was on 9/11” story, for instance, even though in 99% of cases it makes absolutely no difference to anyone but us where we were when the Twin Towers were hit. And we often find ourselves morbidly gripped by all the details – whether that means slowing down to peer at the car crash on the other side of the road, or following minute-by-minute updates from the BBC on the latest terrorist attack.

I like to think this is not because we’re all awful people, but because we have no other way to process the unspeakable horror of what’s happening. There can’t be many of us who haven’t imagined at least once over the last few months and years the very real possibility of getting caught up in a major catastrophe – whether terrorist or accidental – but nobody ever really thinks it’ll happen to them, or knows how they’d react if it did.

This is the inspiration for Stuart Slade’s excellent and thought-provoking BU21, which brings together six young Londoners affected in different ways when a fictional terrorist attack brings a plane crashing to the ground in Fulham, a few months from now. Each has their own story to tell: Ana (Roxana Lupu), horribly burnt and wheelchair-bound after the plane smashed into the park where she was sunbathing; Izzy (Isabella Laughland), who found out her mum was dead through a photo on Twitter; Alex (Alexander Forsyth), whose girlfriend and best friend were killed while in bed together; Graham (Graham O’Mara), an eyewitness who finds himself an accidental celebrity; Floss (Florence Roberts), traumatised by the sight of a man in a plane seat dying in her back garden; and Clive (Clive Keene), a young Muslim looking for answers in the wake of the crash. The fact that each of the actors is, in a way, playing an alternate version of themselves lends the play an unsettling authenticity, strengthened by the fact that the attack hasn’t yet taken place – but still could.

Dan Pick’s production is set in the soulless room where the six meet for their PTSD support group, illuminated by flickering strip lights, and furnished with a few plastic chairs and a metal trolley bearing the obligatory plate of biscuits that nobody ever eats. Yet despite a set-up that should suggest human connection, the majority of the play consists of monologues, with each character speaking into a void while the others deliberately look away.

Each account is horrifically detailed and brutally honest; there’s no glamour here, no tragic heroes, no political correctness or bold display of unity in the face of adversity – there’s just a bloody mess, and a bunch of people trying to pick up the pieces of their broken lives. The characters are not all nice people, they don’t all get a happy ending, and it’s difficult to tell how much support any of them are actually giving or getting as a result of talking things through. In the end, each of them copes in their own way, whether that means milking it or avoiding it, getting on with life or unable to move, seeking comfort or shutting people out.

Slade doesn’t offer judgment or try and tell us who’s right or wrong – if anything, the spotlight is turned instead on our own attitudes. There’s the obvious one, of course, although I can’t imagine many people honestly believed Clive the Muslim would turn out to be a terrorist. But there are also moments that catch us off guard, like when Alex the charming but obnoxious banker suddenly breaks the fourth wall and challenges our decision to exploit his misery for our entertainment. Or every time we laugh – which happens a lot more than you’d expect – always with the uncomfortable sensation that we’re being disrespectful.

BU21 may deal with a terrorist attack, but it’s not a political play; we never really find out who the perpetrators were, and nor does it matter. Stuart Slade’s focus is on the psychology of human beings in a moment of crisis, and while we may not leave the theatre knowing how to survive a plane crash, we might just find we’ve learnt a little something about ourselves.