Stuart Slade's wily, bracing play explores how six millennials are affected by a terrorist outrage that it imagines being perpetrated in a near-future London (22/7/2017, to be exact).

A passenger jet from New York is downed by a shoulder-mounted rocket-launcher, causing hundreds of deaths and horrendous devastation as it smashes into the Fulham area, its engine bouncing down the New King's Road. In interweaving monologues, half a dozen survivors divulge their stories, bringing home both the immediate impact of the attack in their graphic eye-witness accounts of the horror and, as often reluctant members of a support group, the long-term effects of post-traumatic stress.

Izzy found out that her mum was dead on Twitter and is ashamed that her first reaction on seeing the corpse on a social media feed was not one of grief but of physical disgust. The fact that the remains of his girlfriend and his best mate were discovered a week later fused together in flagrante (“like those bodies, you know, in Pompeii”) is revealed with his habitual determined nonchalance by raffish young banker Alex (“it actually made it easier to mourn them”). The main attraction, for him, of a survivors' group is that it is “literally the best place in the universe to pull”.

As you’ll have gathered, the piece eschews any semblance of a hushed, reverential tone in favour of disarming frankness. This can take your breath away with the depth of its moral challenge. Ana, a Romanian waitress who was sunbathing on Eel Brook Common and suffered appalling burns from the aviation fuel, says she does not know whether it’s a miracle or a curse that the human body can live through so much. But she certainly deplores the force – “God or adrenaline or whatever” – that kept a young mother, shredded by the blast down one side “like pulled pork”, in existence for just long enough to learn that her baby had perished. Or the candour can make you gasp with uneasy laughter at the play's refusal to be politically correct and at its determination to question its own procedures.

Though BU21 echoes certain features of 9/11 and 7/7, there's a calculated audacity here in inventing a major terrorist atrocity. Breaking through the fourth wall, the amoral Alex – played with reprehensible charm by Alexander Forsyth – is teasingly complicit with what he regards as the audience's voyeurism, the desire for a “dirty little pervo fix” of misery-porn that he undertakes to satisfy. His job is to bait the punters – as when he accuses us of assuming that Clive, the one Muslim, will turn out to be a terrorist.