Apple Tree Yard review: Slippery about the truth, absorbing till the end

"DNA made me and DNA undid me." So confesses the protagonist of Louise Doughty's 2013 novel Apple Tree Yard, a middle-aged scientist and mother, Yvonne Carmichael, now standing trial for a grisly murder.

Her trial in the Old Bailey is less concerned with DNA evidence, finally hinging on a much more observable detail: the London laneway that she and her secret lover slipped into, at the start of a horrifically fateful night. The side street, sheltered from prying eye and CCTV, gives Doughty’s her title, and a compelling four-part adaptation of the book gives BBC drama a much-needed boost in credibility (BBC One, Monday, 9pm). For its excellent supporting role, London is rewarded with an unlikely new tourist spot: a photo op for fans of forbidden fruit.

Yet the drama all begins, much more slyly, when Emily Watson’s overlooked geneticist follows Ben Chaplin’s security something-or-other into a broom cupboard, in an underground chapel in the bowels of Westminister, where the suffragette Emily Wilding Davison once hid herself in a defiant gesture. In the novel, the suffragette’s sacrifice works like an overwhelming aphrodisiac: “We can sleep with whomever we like,” thinks Yvonne, without fear of pubic lynching: “We are safe, surely.” And so begins an impulsive affair; and so beckons a public lynching.

Adapted by Amanda Coe, who wisely reduces the novel's framing court case and Yvonne's first-person narration, Apple Tree Yard seems to shift through various genres – adulterous romance, spy thriller, gothic horror, revenge tragedy, courtroom drama – but at its heart it is something simpler and older; a lascivious morality tale. First it savours the sin, then it punishes the sinner excessively. Weighed down by the reality of a somnolent marriage and flown children,  Yvonne's affair is a kind of waking fantasy, less compromising than the web of lies she spins to maintain it.

When Yvonne is brutally raped by a colleague, she conceals the event, partly because she fears she will be marked forever by victimhood, but largely to keep her new secrets submerged. The truth might set her free, the show keeps insisting, but it seals us tight into the claustrophobia of her anonymous emails and untraceable phones, awaiting inevitable discovery, like the suffragette in the broom cupboard.

Watson’s understated performance is alive to the clichés of betrayal (“I’ve never done anything like that before”; “This has to end”) but sweetly believeable in Yvonne’s naivety, her face spreading into private smiles or brooding deep in the mirror. “You’re fucking a spook,” she giggles drunkenly at her reflection, intoxicated as much by her own mysteries. Chaplin, suave and swarthy, is kept suitably unknowable, a blank screen for her projections.

Rape on television is often an unthinking plot device, used to destroy women or spur avenging males. Here, mercifully, Yvonne is not diminished; damaged but not destroyed. As the story gets darker, turning through consequences and revelations (rather than twists), it’s her power, more than her lover’s, that comes under close examination. She can influence others and deceive herself. Director Jessica Hobbs rations out plot details in a model of fleet visual storytelling and elliptical ambiguity. In her shots, the details of London tend to dissolve into soft focus, all watery blues and burning orange, as though the narrative winds between a daydream and panic of wakefulness.

This is also the effect of its finale, set mainly in court, where Watson peers at witnesses through distorting glass panes, and Chaplin, silent throughout, seems to shrink as his character becomes more real. The scientist’s faith in reason abandons her as she awaits the verdict. “Courts aren’t about the truth,” Yvonne thinks, in Watson’s subdued voice over, “but about who tells the best story.” That seems a more accurate description of the programme, though; one whose story is both slippery with the truth and absorbing until the end.