Young adulthood can be stifling. Throw in the expectations of a religious community and it can become more claustrophobic still. This breeds secrecy – and Mundill Mahil’s life was full of secrets. There was her relationship with Gagandip Singh. And then there was the boy she called “my gangster friend”, Harinder “Ravi” Shoker. Ravi smoked and drove a car without insurance. For the strait-laced student doctor Mundill, he represented quite a walk on the wild side.

The case explored in this gripping factual drama was, in typical tabloid style, branded “the Honeytrap Murder” in 2011. But the reality behind Gagandip Singh’s tragic fate would be much more challenging for a red top writer to turn into a crass headline. As presented here, Gagandip’s killing was less a crime of passion and more a product of confusion.

Vengeance: Murder on the Heath is written by Aysha Rafaele (who won a Bafta for the harrowing Murdered By My Father in 2016) and executive-produced by Joseph Bullman, who was responsible for this year’s water industry polemic Dirty Business. Their films share a lingua franca, often somewhere between urgent drama and carefully presented facts. This two-part series is similarly constructed: dramatic segments are punctuated by straight-to-camera, documentary-style reflections of the characters. This stylistic technique represents the subjectivity of the multiple perspectives involved; the certainty that fact and fiction mean different things to different people.

And in this case more than most. Gagandip (Dee Ahluwalia) was a prototype influencer; a self-made media personality within Sikh community circles. However, the conflict between his religious piety and his more earthly impulses soon became a problem. His friendship with Mundill (Sasha Desouza-Willock) developed into a one-sided fixation, accentuated by the sudden death of his father. He proclaimed his love for Mundill. He started turning up unannounced at her student digs in Brighton. “At times,” says Mundill, “it felt like emotional blackmail.”

Meanwhile, a very different story is being told by Gagandip’s mother, Tajinder Kaur (Laila Rouass). From the start, she suspected that her son was being manipulated by Mundill. Rafaele’s script does a meticulous job of giving these varying perspectives equal weight. Accordingly, there is a chance that this drama ends up pleasing no one – but that might even be a feather in its cap.

Gagandip’s adoration of Mundill was not to be easily denied. Eventually, he contrived an excuse to stay on her couch – he told her his car had broken down. He tried to seduce her. When that failed, he sexually assaulted her. This scene is the grim heart of the story and it’s brilliantly played: simultaneously horrifying and pathetic. When Mundill fights him off, Gagandip tries, pitifully, to put the shattered fragments of their trust back together again. It’s an acute portrait of fragile masculinity – the violence is fleeting and both its prologue and epilogue are wheedling and desperate. “That wasn’t me,” he whimpers. “You know that wasn’t me.”

But it was him. And so, re-enter Ravi Shoker (Ikky Kabir), who is also besotted with Mundill. Along with his friend Darren Peters (Badger Skelton), the pair decide to teach Gagandip a lesson. Whether this will involve violence, a firm reiteration of religious ethics or a mix of the two is, fatally, never quite decided. But it culminates in Gagandip being lured to Mundill’s flat (which is inconveniently full of her bewildered student housemates) where he is beaten before being bundled, unconscious, into Ravi’s car, which is driven back to London and set on fire.

“Why didn’t you help him when he called you?” asks one of Mundill’s horrified roommates afterwards. “I don’t know,” she replies. This feels like the clearest, most honest line in the drama. There can be an issue with keeping character development, intention and narrative balance poised so ambiguously throughout a story. You risk the audience ending up none the wiser about any of these things. This pitfall is avoided thanks to the performances, which illuminate the flaws, failings and muddy motivations of everyone involved. Mundill’s emotional paralysis. Gagandip’s entitlement. Ravi’s jealous rage. Eventually, Vengeance: Murder on the Heath becomes an unflinching study in weakness, bad faith and botched communication. It spares no one.

This is a drama rooted in a particular version of the British-Asian experience. The perceived expectations of the community are a constant backdrop to this downward spiral of terrible decisions. And yet the story is sadly universal, too. It’s full of alpha jousting between emotionally underdeveloped young men with toxic crushes. A young woman who is both a victim and an instigator of forces she can’t control. And a bereaved mother, unable to process what has been taken from her.

Crucially, it retains compassion for everyone involved. Not a “honeytrap murder”, then, but something far sadder. A terrible waste.