God of Carnage, Gielgud Theatre, London

Imagine a supremely awkward social situation and multiply it by 10. Not today's state meeting between President Bling-Bling and the Queen but the nightmarish scenario cooked up by Yasmina Reza in her new play.

The Parisian playwright, who last year published an intimate biography of Nicolas Sarkozy, has returned to the UK for the first time since 2000, hoping to emulate the phenomenal success of her 1994 play Art, reuniting with director Matthew Warchus and translator Christopher Hampton. But however much the audience roars with laughter at every opportunity and cheers on the heavyweight cast – Ralph Fiennes, Janet McTeer, Green Wing's Tamsin Greig and Art alumnus Ken Stott – it doesn't shine.

God of Carnage portrays two sets of middle-class parents in a crisis summit to discuss a brutal playground fight between their sons. What begins as an agonisingly polite discussion over espresso, rapidly deteriorates into a farcically awful, rum-fired slanging match.

Stott rants and raves like a madman and McTeer as his bleeding-heart liberal wife is a wonderfully comic mixture of earthiness and brittleness. Greig also explodes into life after a quiet start, deploying her considerable talent for (unpleasant) physical comedy and a maniacal cackle. But Fiennes never convinces as Alain, her boorish, plain-speaking lawyer husband. He is not a natural comic and his bone-dry one-liners often miss the mark.

There are gasp-worthy moments of rudeness as the characters switch allegiances and vie for attention like the spoilt brats they are discussing. But often they are lost in Warchus's stilted production.

Reza has proved that she can skewer the middle classes like no other, revelling in the grotesque prejudices not only of her characters but also of the audience. This time though, the playwright has done it almost too well, to the point that her play becomes nearly unwatchable. It's clear that Reza wants to confront bigger themes but it's a direction which sits uncomfortably with her penchant for broad humour and this curious hybrid of Who's Afraid of Virginia Woolf and Ayckbourn-esque farce left me feeling distinctly queasy.

Booking to 14 June (0844 482 5130)