The life of a man, said the philosopher Thomas Hobbes, is nasty, brutish and short, and the same could be said of this stunning almost first play by 25-year-old Mike Bartlett – I have seen an even more complex, remarkable Bartlett play about racism and peer group pressure in the Hampstead Theatre’s Heat and Light young people’s programme - but he must count on the record as yet another highly promising graduate of the Royal Court’s Young Writers Programme.

The Downstairs auditorium has been obliterated by designer Miriam Buether. The audience enters a tunnel that might well be a carriage on the Jubilee Line, with yellow tubular poles and handrails, where a young boy chases an electrified model car and actors you recognise – Ben Miles, Sara Kestelman, Jan Chappell, Lia Williams in a bright orange hair-do – pretend to blend in. We’re standing in a space that does not want to be in the Royal Court but take us elsewhere.

The more indolent first night critics and guests chose to sit on bar stools running behind a thin aluminium table redolent of Eurostar. The rest of us stood around two raised terraces, arranged traverse-style, like rush-hour city commuters. One bar-stooled critic received a wake-up call when Miles kicked in a waste canister right by her writing arm. The theatre’s chairman chuckled. The theatre’s former casting director was in tears.

What might seem precious turns out to be anything but. Miles plays Man whose son, the boy, has been wrested from him after a split with Williams as Woman. Kestelman is Williams’ incontinent mother, Chappell a less insistent presence as Miles’ mother. No one in this play has a name apart from the boy’s “new Dad,” Karl (Adam James) who confronts Man after he has abducted Child and punches his lights out.

It’s not that good, really, and too sentimental, but what I like about Bartlett’s play is its simplicity and starkness, its realisation that to make good theatre you can pare right down to basics and raw emotions, and honest dissections of relationships, like you can lacerate them. The play – which runs for just 45 minutes – is written in flinty, aggressive dialogue with one or two really potent, poetic paragraph speeches.

Man has a crisis of masculinity to deal with as well as a stifled paternal role, and Miles plays this with a fierce concentration that is almost overwhelming. He is jeered at by Williams’ rather nasty Woman, despised by his own son, humiliated by a prostitute who offers a blow job. And yet he is still the character we like most at the end. Little Adam Arnold’s coldly manipulative, but vulnerable Child, is a complete pain. “I don’t like books,” he says, “they’re gay”; brilliantly acted, though.

The direction by Sacha Wares – her debut as one of new artistic director Dominic Cooke’s associates – is outstanding. The play is pitiless and horribly convincing, the presentation lively, different, and interesting. You feel that if we do have to have yet more misery, and more proof that children rarely get the parents they deserve, let’s at least have all this bad news with some theatrical panache. And that, in this case, we have, in spades, and in the performances of a remarkable cast.

- Michael Coveney