First Night: Honour, Wyndham's Theatre, London

For decades, the stock sneer at the English novel has been that it is preoccupied with "adultery in Hampstead" - successful, moderately intellectual couples in expensive houses suffering mid-life crises. As a result, no novelist wanting to be taken seriously will now touch the subject with a bargepole, and the angst of NW3's adulterers has been left unchronicled. Luckily, Joanna Murray-Smith's play Honour fills the gap very nicely. In fact, it started life as a play about adultery in Murray-Smith's native Melbourne; but the location has been shifted to Hampstead to suit British audiences, and it seems to have lost nothing in translation.

The couple at the centre of the action are George (Martin Jarvis), a distinguished highbrow journalist, and Honor (Diana Rigg), in her youth a celebrated poet, but who gave up the literary life in favour of motherhood and George's career. Their comfortable existence is disrupted by the arrival of Claudia (Natascha McElhone), a beautiful and fiercely ambitious young writer, who is doing a profile of George.

It's not long before George is informing Honor that while he still loves her, he needs more than their marriage can give him, and she is making speeches about the meaning of loyalty.

The speeches are well-turned. At her best best, Murray-Smith demonstrates a Stoppardish gift for pithily combining intelligence, wit and pathos. Confronting her rival, Honor asks what Claudia thinks will happen when she, too, starts to look old. "I take care of myself," Claudia brags, to which Honor offers the deeply gloomy riposte, "Time takes care of all of us." But the speeches never add up to convincing characters: "We are guilty of liking words more than people," Honor tells George, and that charge could be levelled at Murray-Smith, too. The characters chuck accusations, apologies, reproaches at one another in a somewhat mechanical fashion, as if trying out all the permutations rather than living out actual problems. The smoothness is ruffled somewhat in scenes involving the couple's distraught twentysomething daughter (Georgina Rich): but here the dialogue falls into patterns of hesitation and repetition straight out of the David Mamet playwriting manual.

Still, the play does offer meaty parts for the leading actors - Eileen Atkins walked off with an Olivier for playing Honor in the 2003 British premiere at the National Theatre. Diana Rigg is unlikely to repeat the trick, with a performance that errs on the side of understatement, but is still appealingly humane and gentle. Jarvis is unfortunately cast as George, never projecting enough intelligence or passion to overcome the slightly cardboard lines he is given; and while McElhone gives Claudia a plausibly brittle, mechanical quality, she is likewise trapped into playing a type rather than a character.

Given the number of good lines, and the brevity of the piece (one hour and 40 minutes), it could be the basis for an enjoyable night out. But that's not quite the same thing as a satisfying play.