There is no pool so stagnant that an adroitly thrown brick cannot produce ripples. In this American comedy, which won its author, Gina Gionfriddo, a place on the Pulitzer shortlist in 2009, the stone is Becky Shaw, a lowly single secretary out to get a man before her thirties run out. The murky pond is the Slater family, a Franzen, one might say, of psychological tensions, economic stringency, verbal super-fluency and ego. When this needy intruder from a slightly different economic subset (if you still believe the US is a classless society, get thee to Islington) plops into their lives, they are first sympathetic and then amused. But the churning starts and soon Becky has induced panic all round. It is uncomfortably funny.

The Slaters' matriarch is Susan, queen of the reductive one-liner. A parental death, she tells her daughter, keeping warm the memory of
her recently deceased father (and Susan's husband), is not a distinction but the "commonest of milestones". But although mercilessly insightful about others, she is incapable of criticising the ne'er-do-well who is her new lover. If you hope her daughter, Suzanna, and her adopted brother, Max, might cut her some slack because of her MS, you mistake the family.

Instead they do their best to persuade her that her late husband was gay. Yet, as played by the ramrod-backed Haydn Gwynne, Susan may be the play's least vulnerable character.

The play opens with 34-year-old Suzanna (Anna Madeley) in a hotel room in New York where she is wallowing in real-life crime on television because it "soothes" her. Max enters and orders: "No more dead prostitutes on the autopsy channel." In a pretty schematic way, Suzanna is the emotionally attuned sibling and Max is the cynical rationalist. The complication is that Suzanna enjoys the drama of her feelings, and Madeley gets over the suggestion that she is a suppressed non-hysteric very well.

Soon she has married a dim but virtuous non-achiever named Andrew (Vincent Montuel), whose credibility is undermined by the actor's initial, unshirted appearance: a man with pecs like those cannot be taken seriously by a family like the Slaters or an audience like the Almeida's.
We are meant, however, to be most interested in Max, whose cool wit, scepticism and studied shallowness (he likes porn, sees no point in discussing politics) cover, naturally, much inner turmoil. Chief of these is his near-incestuous love of Suzanna, who, in the first scene, unwisely sleeps with him.

David Wilson Barnes, who has played Max in every production of the play so far, is Kevin Spacey crossed with Chandler Bing and certainly owns the part, but it is not quite the peach he must have been told. Max's sarcasm is rarely as clever as he, or his playwright, thinks it is.

So we meet, rather late, Becky Shaw, with whom Suzanna has set him up. Their date is the first of two very strong scenes in the play. Max first dismisses Becky, who arrives in Suzanna's apartment looking, as Max says, like a "wedding cake". But, with his expectations set to low, she surpasses them by showing signs of intelligence. They dine, they get mugged, they sleep together. A stalker is born, but a slightly incompetent one. The play's second first-rate scene is when they meet for coffee and M tells B he is just not that into her and B retaliates with blackmail. Daisy Haggard plays Becky brilliantly but, done up to resemble The X-Factor's Stacey Solomon, is horribly miscast. Becky is meant to be a beautiful woman - the play's title is a reference to the anti-heroine of Thackeray's Vanity Fair - victimised by bad luck. Here she
is a grotesque.

The play takes Max's side, not in the sense of excusing his behaviour but in endorsing his and his stepmother's dry-eyed world-view. Imagine my surprise on reading Gionfriddo's note to her text and discovering that she thinks none of her characters is "bad or wrong or crazy or worthless or unlovable". She regrets that her audiences "point fingers". This is sanctimonious twaddle. Gionfriddo pees on her creations from a very great height. Her play is about as empathetic and charitable as Max. It's good, nasty fun, but the Pulitzer committee was surely right to pass on it. l

Andrew Billen is a staff writer for the Times