Seven summers ago, fifteen year-old Thomas Devlin died in an unprovoked knife attack, a few hundred yards from his home in the leafy suburbs of north Belfast. The teenager and some friends were returning from buying sweets in a local garage when they were pursued and set upon by two men from a nearby loyalist estate. In the intervening years, his parents Penny Holloway and Jim Devlin have earned nothing but respect and admiration for the dignified manner in which they faced up to this unforeseen tragedy, as well as for the various funds and initiatives they have set up in memory of their son.

But behind closed doors, away from the glare of publicity, they doubtless suffered the same agony of soul-searching and questioning as Mary and John Pritchard, the central characters in Shelagh Stephenson’s critically acclaimed play The Long Road, here receiving its first production in Northern Ireland. Premiered at London’s Soho Theatre in 2008, it was not specifically written about the murder of Thomas Devlin - but it could have been. The senseless, random act of violence, which ended Thomas’s life, has been replicated many times up and down the UK and Ireland. Unhappily, knife crime in inner-city areas has become a universal story for our times.

It was a spate of street killings in London which prompted Stephenson to link up with the Forgiveness Project, a charity which works in the areas of reconciliation and restorative justice – both of which remain pressingly pertinent issues in post-ceasefire Northern Ireland. Her meticulous research brought her into direct contact with victims and perpetrators, with whom she talked at length about the effects and motivations behind those brief moments of madness, which not only destroy lives but forge unlikely, unbreakable bonds of shared experience between families.

In the flexible space of the Lyric’s Naughton Studio, director Richard Croxford has opted for a production that is halfway between traverse and in-the-round. The audience is seated on three sides of the performance area; the fourth side is occupied by a floor-to-ceiling photograph of a good-looking, carefree teenager. He is - or was - Daniel Pritchard, a bright, sociable aspiring lawyer, wiped out by a single stab wound inflicted by Emma Price, an aggressive young girl from a severely disadvantaged background, who later admits to having been “off her face” at the time. As the action unfolds, the space divides between a prison visiting room and the home of the bereaved family – Dan’s mother Mary, father John and brother Joe, still haunted by the mistaken belief that, in the eyes of his parents, the wrong son was taken away. The staging confers onto the audience the role of close-knit confidants and witnesses, while the generic, uninspiring set provides scant visual diversion, consisting merely of a table, four black plastic chairs and a stripped pine display cabinet, on which sits a yellow china urn containing Dan’s ashes.

The play begins and ends with a series of interlocking monologues, nicely set up by Chris McCurry’s downbeat, reflective Joe, whose quiet, apparently non-reactive manner barely disguises the lingering hurt of cradling his dying brother in his arms as the blood from a pinprick wound oozed across his shirt “like a big red chrysanthemum.”

Sheelagh O’Kane’s tear-stained face and pent-up bearing poignantly convey a mother’s grief, veering between denial, fury, incomprehension and the pressing need for an answer to the big unanswerable question – why? In one of several searingly frank confessions, she admits to the temptation to sprinkle her son’s ashes onto her breakfast muesli and consume him back into the body from whence he came. In contrast to her unfettered outpourings, her husband can find no verbal expression for his loss. Suppressed tension exudes from Brendan Fleming’s automaton-like John, drowning in silence, alcohol and disbelief at his wife’s desire to meet and understand their son’s killer.

In spite of her husband’s disapproval, Mary does meet Emma in a fractious encounter, facilitated by Jo Donnelly’s well-intentioned prison visitor Elizabeth. Donnelly’s is a calm, interventionary presence, soaking up Emma’s wise-cracking anger, while attempting to persuade her to take responsibility for her actions. The first exchange between victim and aggressor is finely handled, with O’Kane reacting as any bereaved mother would to the callous, unrepentant demeanour with which she is received. On her return home, Fleming finally hits his stride as he struggles to refrain from telling his wife that he told her so.

In her fierce refusal to read the letters sent to her by Mary, it is not difficult to discern the bottom line of Emma’s problem, whose revelation signposts a sentimental and superfluous final scene. Punctuated by passages of touching honesty, Stephenson’s sensitive script scores high on detail and authenticity, while being occasionally repetitive and self-evident. Its rhythms do not entirely chime with the Northern Ireland speech patterns and occasionally elude even the strongest performances. The exception is Bernadette Brown, cast, as usual, as a hard-faced, aggressive, lippy young woman and delivering Emma’s torrential musings on drink, drugs, poverty and parental neglect in a Belfast accent which would strip paint.

What will remain most strongly etched in the memory is John Pritchard’s quiet affirmation of his slow progress in coming to terms with the loss of his son and its devastating effect on the equilibrium of their once-solid family unit. He yearns for dignity in carrying his grief, for it is dignity, he says, that makes us human. Northern Ireland has witnessed the truth of this deceptively simple statement many times over the past four decades. Forget the final scene. It is here that this important, insightful play should rest its case.

Jane Coyle is a Belfast-based arts journalist, critic and screenwriter, who also reviews for The Irish Times, The Stage, Culture Northern Ireland and BBC Radio Ulster.