Like me, audiences might be forgiven for not knowing that ‘Wastwater’, the title of Simon Stephens’ new play for the Royal Court, refers to the largest valley of water in England. Audiences might also be excused for failing to realise that this behemoth of a lake reaches nearly three-hundred feet in depth and is located the Lake District. Further still, audiences might be pardoned for struggling to comprehend its relevance to a play located on the outskirts of Heathrow Airport’s Terminal 5. However, having had time to digest this mysterious and disturbing work, it becomes a fitting metaphor for the fractured relationships that Stephens makes us encounter.

Like the deceptive calm of the lake’s glacial surface, Stephens’ characters conceal the ravages of their shipwrecked lives. Each of the play’s self-contained two-handers escalates from mysterious encounters and vague farewells, into intensely destabilising admissions of violence, deceit, subterfuge and degradation. Set across three locations on the peripheries of Heathrow Airport, the overwhelming mood is one of liminality and stasis: Frieda and Harry are on the verge of a pained farewell on the porch of their cottage; Mark and Lisa’s hotel liaison marks the brink of a sexual betrayal; while Sian and Jonathan’s meeting in a warehouse reveals a fatal transaction at breaking point. The scenes are punctuated by the  sounds of passing planes criss-crossing each relationship; their piecing tones become a cruel reminder of  listeners entrapment, as they orbit a constant desire to escape.

Escape is a never-ending compulsion in Wastwater. While Harry’s imminent journey to Canada offers him the hope of a fresh beginning, Mark and Lisa’s sexual transgressions embody a visceral desire for renewal that verges on the pathological. Meanwhile, Jonathan’s entanglement in the sinister machinations of Sian’s business deal affords no escape, despite his attempts to tear free of its consequences. Even the environments themselves appear to be breaking free. Lizzie Clachan’s astute design portrays the outside world laying siege to the interior realms of the characters. Frieda’s cottage is crumbling edifice of glass and stone, overrun by the local flora. Water infiltrates the warehouse through its cracked surfaces and even the privacy of the hotel suite is bombarded by the outside chaos of the digital world. Like the airport’s monolithic promise of escape, always in sight but somehow out of reach, the overwhelming feeling is of encroaching stasis and reckless transgression.

Interestingly, Wastwater‘s three acts avoid the unwritten rule of temporal chronology. Instead, the scenes unravel simultaneously, paralleling each other in significant and subtle ways. The allusions to each form a complex web of implied relationships and potential affiliations. Upon each new revelation, I found myself revising previously safe impressions of the characters. Is Frieda simply Harry’s foster-mother, or does she harbour disturbing links to Sian’s child-trafficking racket? Is Jonathan the tragic victim of coercion or does his history of professional misconduct harbour a more disturbing reality? No finite answers are provided. What we’re left with is an unsettling sense of suspicion, as each character slips free of our grasp and each new secret is unearthed.

Katie Mitchell orchestrates the action with a pitch-perfect attention to each individual scene. Indeed, her direction appears to treat the ebb-and-flow of each act as movements in a symphony: the gentle lyricism of Frieda and Harry’s farewell escalates towards the intensity of Mark and Lisa’s sexual violations, before crashing back to earth in the final menacing encounter between Jonathan and Sian. The actors temper their performances wonderfully for each of these acts and each performs with a keen and intelligent intuition for the variegated tone of the play. However, particular praise must go to Jo Mcinnes for her accomplished performance as the self-destructive Lisa. Combining a sardonic wit with intense pathos, Mcinnes renders Lisa hilarious and alarming in an unsettling but riveting portrayal.

Wastwater delves into the bleakest and most intimate depths of human relationships. Stephens’ combination of black humour and emotional insight has crafted a play that combines agonising moments of terror with moving sensitivity.  Those seeking security and closure might be disappointed. However, like Stephens’ best work, Wastwater challenges its audience to think through its ambiguities and fill in the unspoken gaps. Like the airport, hovering luminous on the margin of sight, Stephens’ Wastwater will remain on the edge of your vision long after the curtain comes down. A haunting presence.

Wastwater is playing at the Royal Court Theatre until 15th May. For tickets and further information see the website here.