Boarding school, in film and television terms, tends to fall into one of two categories. There’s either the sweet, rosy glow of nostalgia that reflects on class barriers being broken, lifelong friendships being made and lessons being learned. Or there’s the brutal, class-driven, punishment-laden and spirit-breaking kind of educational institution. Walter Presents latest six-part drama, Evil, is firmly in the latter camp.

Evil is likely to be called a morality tale, a warning as to what happens when we don’t stand against certain behaviours. At times, it feels more like a nightmare; a labyrinthine punishment from which there is no clear exit. The series is based on Jan Guillou’s novel, Ondskan, which he states was based on his own grim experiences of boarding school.

The series opens with a young man being beaten to a pulp, begging for his life to be spared and sputtering out apologies in amongst gulps of glossy maroon blood. A silky voiceover reminds us that no one is “born evil … We’re born with all the possibilities inside us.” But for Erik Ponti (Veronika’s Isac Calmroth), there doesn’t seem to be so many possibilities as to where his life is headed. Since he was the one throwing the punches in those opening minutes, his mother (Ruth Vega Fernandez) and stepfather (Gustaf Skarsgård) decide to ship him off to boarding school. Within moments of arriving at the opulent grounds of Stjernsberg, he is plunged into a system that is every bit as brutal as his ‘previous life’. Can he break this cycle of abuse and humiliation? Or is he part of a chain that will continue for generations to come?

The series is tinged with a sepia yellow that, in some cases, may connote a cosy glow but, here, makes everything feel putrid. Although it’s set in the 1950s, Evil is most definitely not all swing skirts and pompadours. The colour palette is awash with mahogany browns, yellowy creams, deep maroons and fusty greens. The lemon walls of the school building may seem soft and inviting but they are home to a misogynistic, classist and violent sect of Prefects whose legacy and family wealth save them from any real consequences. To begin with, Erik is a leather jacket and pursed lip amongst a herd of uniformed masses, complete with pinky rings and gold watches. But as soon as he dons his blazer, he is thrust into a system that seems intent on eating him alive.

To carry off such heavy material, you need a stellar cast. And Evil delivers on this. Isac Calmroth offers up a performance that moves through quiet defiance, terror and steely resolve. Erik is a young man who has never been able to see beyond violence because it is such a core part of his home life. Whilst other school boys bow their heads in fear of being called upon, he is not afraid to look someone in the eye and call out their behaviour. Calmroth’s performance is gentle where it needs to be whilst also being full of a mixture of both rage and grief. He is thoroughly compelling across the entire series. As his nemesis, Otto Silverheilm, A Nearly Normal Family’s Christian Fandango Sundgren is all chiselled cheekbones and glacial blue eyes. He is a character everyone will love to hate, so riddled with class prejudices and self-aggrandisement it practically ripples off the screen. He’s a bully, a big fish in a small pond: a character whose comeuppance you can’t help but wish for. Sundgren brings all these facets to life with merely an adjustment of his signet ring or a quietening of his voice. He feels truly threatening, which is no small feat.

Gustaf Skarsgård is equally awful as Erik’s violent stepfather, Åke. His pencil thin moustache, three strand combover and wiry frame do not suggest a physically dominant man but every time he appears on screen, you cannot help but wonder which perceived slight will unleash his true, abusive self. The danger radiating off him feels palpable. You will be torn between and Otto for odious TV villain of the year. (Coincidentally, the book was made into a film back in 2003 where Skarsgård took on the equally villainous role of Otto). Åke is genuinely frightening – with episode three as a stand out. Alleviating things is The Last Kingdom’s Thea Sofie Loch Næss as Marja, a “domestic” within the school. She is gentle and kind; a young woman whose early life has instilled in her a clear sense of morality and empathy. Whilst not the most imposing performance within the cast, her character is certainly an important counterbalance to the rest of the traumatic goings on.

It’s the violence and cruelty of the characters that is likely to stick with many viewers long after watching this series. For this reason, a binge-watch may prove too heavy for some. While gratuitous and hauntingly lifelike, it is used to make a point. Whether that’s about a particular character or about cycles of abuse more generally. Both Åke and Otto use violence as a way of humiliation and control; they lack the self-confidence or position in life they truly covet. Erik, conversely, uses violence because he doesn’t know any other way of “winning”. He cannot see a way out beyond using his fists. Thus, the notion of generational trauma is touched on. “Life is a choice,” as the voiceover says. Is Erik’s way out as simple as that?

There is also a kind of violence in the “not doing”. Both Marja and Erik’s mother express their regret in “not doing”, in allowing patterns of behaviour to have drastic and life-altering consequences. More than this, the teachers at Stjernsberg see and hear exactly what is going on but choose to shut themselves away from reality. They allow these class-dominated systems of abuse to continue in order to keep donor parents and legacy pupils happy.

Evil is a harrowing and compelling series that sets clear lines between good choices and bad; right and wrong. Although life itself isn’t perhaps as simple as that, the series doesn’t lose any of its impact. The violence and abuse on the show are relentless in their humiliation and injustice. This is a thoroughly well-acted, well-written series that isn’t afraid to tackle hard subjects. There’s flesh on these characters … even if it is bloodied and bruised.

Evil is released on Walter Presents/More 4 from the 16th August