Nobody does emotional blackmail better than Polly Stenham — or, rather, her characters. Demands made by a wreck of a mother wreaked havoc in the 19-year-old playwright’s assured, awards-laden debut “That Face.” Three years on, despite no mother being present, the damage caused by parental selfishness masquerading as selflessness charges the air of her second play, “Tusk Tusk.” Stenham herself makes major demands — her three lead characters are aged 15, 14 and 7 — but Jeremy Herrin’s meticulous direction allows her adult themes to grip with cumulative power.
The play’s least complicated relationship — or so it seems — is between 15-year-old Eliot (Toby Regbo) and his 14-year-old sister Maggie (Bel Powley), who are relishing the freedom to do what they like in their mother’s brand-new flat. Though they comically jockey for position and constantly pull rank, their differences pale beside a shared love for kid brother Finn (played with uncanny poise on press night by Finn Bennett).
Yet Stenham’s acute sensitivity to the allure and danger of love means that not only is she intent upon dramatizing the idea that relationships have boundaries, but she’s equally aware of people’s propensity for crossing them.
She cunningly balances gleeful home-alone sibling revelry with a growing sense of disquiet among the characters and the audience. The longer they wait for the return of their worryingly absent mother, the more pronounced the pressures and distances between them become.
As they live day for night so as to be more invisible to the outside world, their idleness turns to restlessness until desperation sets in. While the increasing emotional savageness might suggest “Lord of the Flies,” not only is Stenham’s timeframe tighter, but her aims are less anthropological and more focused on personal responsibilities.
Dealing with their mother’s perilously fragile mental health has made both Eliot and Maggie grow up too fast. Their ricocheting between prematurely adult self-awareness and childlike neediness is perfectly calibrated by Herrin’s direction of the actors, both making their professional stage debuts.
As Eliot, rangy, pale Regbo, 17, maintains impressive physical control even as events threaten to spiral out of his grasp. Under duress in the more fiercely driven plot scenes that kick the second act into alarming relief — where real blackmail suddenly becomes thrillingly manifest — Regbo never overplays the sadly misplaced hope that drives him.
Maggie is younger than her brother, but Stenham invests her with disarming maturity, a quality effortlessly captured by 16-year-old Powley. On Robert Innes Hopkins’ naturalistic set of an increasingly chaotic ground-floor apartment, she commands attention. Her baleful face is transformed by tiny flickers that silently evoke years of coping with undue strain.
The entire cast is good at swapping the script’s amusingly self-aware banter. That so little of the dialogue is quotable actually indicates the strength of Stenham’s writing, its snappy, tight exchanges replete with subtext and silences fraught with tangible tension.
Not everything works. The ultimately repetitive nature of the situation makes for some repetitive writing and the character of Eliot’s new-found working-class girlfriend, Cassie (Georgia Groome), feels too much like a device to indicate Eliot and Maggie’s middle-class complacency. Although the arrival of two of their mother’s well-meaning friends late in the proceedings triggers the climaxes, the plotting stutters rather than flows.
Yet the sadness of the closing scene is testament to the play’s affecting ache. The raw tenderness of her examination of love gone awry in both “That Face” and now “Tusk Tusk” marks Stenham as an excitingly idiosyncratic theatrical voice.