A spoonful of poison.

Opening on a yuppie-chic kitchen, all marble surfaces and gleaming chrome, Nancy Harris’s savage new play takes less than sixty seconds to grab you by the throat so hard your eyes water, if you can keep them open at all. Our New Girl is a formidable slice of North London Gothic, with dialogue as sharp as a Sabatier and a sense of dread which swells to unbearable peaks. That many of the component parts are familiar only strengthens its ability to wrong-foot an audience, Harris has constructed a very modern psychodrama, and this production realises it with a fierce glee.

Hazel Robinson (Kate Fleetwood) was once a high-powered lawyer, now confined to a life of domesticity and weighed down by her imminent second child. The play begins with the unexpected arrival of Annie (Denise Gough), an Irish au pair arranged by Hazel’s husband Richard (Mark Bazeley), a prestigious plastic surgeon. Their young son Daniel (Jonathan Teale on press night, though the role is shared) seems to be suffering from emotional problems, and Hazel is struggling to cope. The unsold bottles of olive oil which represent her futile stab at entrepreneurship mount up alongside her stress levels, and Annie’s presence begins to open sinister fissures in the Robinson’s apparent urban idyll.

Flickers of Rosemary’s Baby and The Omen glint across its surface, but Harris’s play is founded in far more conventional and disturbing horrors. Hazel’s descent into paranoia is perfectly pitched in a cracking performance by Fleetwood, who has discovered a vulnerability in pregnancy which could never have assailed her in the courtroom. Richard is a brilliantly grotesque creation, a self-obsessed grief-junkie one step shy of outright parody, his brand of White Knight chauvinism is captured perfectly by Bazely. Gough is best of all, so unassuming that it is impossible not to expect the very worst. The cast is rounded off with a great performance from Teale in a demanding role, without a doubt one of the best child actors this side of Matilda.

Charlotte Gwinner directs with an excellent ear for the play’s humour as well as a strong sense of mounting horror. Moments in which Hazel’s difficulty in understanding Daniel’s behaviour crystallise into outright fear of his intentions are taut without succumbing to cliché, and Harris’s text has been given ample room to breathe in Gwinner’s well-paced confrontations. Morgan Large has succeeded in bringing the epitome of smug kitchen to the new Bush, his showroom-like design both the perfect mask of success and a prime location for catastrophe, its knife rack glinting with implied threat. Hartley Kemp’s lighting design initially feels incomplete, with no sense of the passage of time or hint of natural light, but this works strangely well as we see the characters locked in a cold and unnatural world utterly unreceptive to their pain and their struggles.

Plot strands featuring a nearby cocktail party and inappropriate pet feel somewhat directionless and laboured but these (very) minor problems aside Our New Girl is a terrific play. A sort of Mary Poppins where Mr Banks is a lecherous Bear Grylls and Mrs Banks a baby-step away from disintegration, Harris should be very proud of this fiendish spoonful of poison.