Herman Koch's The Dinner is, like Christos Tsiolkas's The Slap, a novel whose premise can be neatly reduced. Two couples meet in a fancy restaurant in Amsterdam to discuss an outrage perpetrated by their sons. As the evening progresses, civilised behaviour breaks down, revealing that the parents are not so different from their children.

Roman Polanski's 2011 film Carnage covers similar territory; the urbane, liberal sheen is quickly rubbed off two sets of New York parents when they meet to discuss a fight between their sons. In The Dinner, although the boys may be products of their parents, they come from two very different families, and the grotesqueness revealed in the novel is of a different order.

The boys' fathers, Paul and Serge Lohman, are brothers. The narrator, Paul, is a teacher "placed on non-active", while Serge is a charismatic politician in the running for Holland's premiership. The book is divided into courses, and during the aperitif and appetiser it's hard not to side with Paul's assessment that his richer, better looking, more popular brother is overly smooth, insincere and sexist. Many readers will be inclined to meet Paul halfway on this; after all, even when we're voting for them, who really trusts a politician?

Paul's voice is initially beguiling. He describes Serge's rural retreat in France as having "a whiff of Boursin  imitation cheese that had nothing to do with French cheese". But as the novel progresses on to the main course, it becomes increasingly clear that Paul's jibes may not simply be attempts to puncture his brother's hypocrisy. What qualifies him to label Serge a hypocrite? For instance, there is nothing except Paul's insistence that Serge and his wife do not really love their adopted son Beau as much as they love their biological children.

The differences between the brothers might suggest that nature and nurture are equally irrelevant, but family bonds are important to Paul. His  intense love for his only son Michel is matched by the devotion he feels for his wife Claire. Three-legged structures are the strongest, and together the trio are solid. When Michel and his cousin commit their terrible act, Paul and Claire are forced to decide where their loyalties lie. Are they confined to their small family unit or do they extend to the human family, society? Will the couple sacrifice one for the good of the other?

Paul recognises the liberal values professed by his country and his politician brother. He understands the unfairness of sexism and racism and has no problem with homosexuality. Paul is also empathetic, up to a point. He remembers how the face of a schoolchild to whom he said something unrepeatable "broke down the middle. Like a vase. Or like a glass that shatters at a high pitched note", but it gradually becomes clear that Paul's keen sense of observation and tendency to analyse others are symptoms of his own dislocation. For Paul is a violent man who needs medication to control his impulses.

Koch paces his revelations expertly, and there are twists and turns enough to keep us reading, but his decision to ascribe the former teacher's violent outbreaks to a biological defect  to make Paul's condition something other than simply the human condition  diminishes the book. Paul is clearly not "one of us", whoever "we" may be. But The Dinner is more than its plot, and Paul's voice, combined with his knowledge of his own flawed personality, has the potential to sustain the novel without the drama of the two boys' transgressions and their parents' divided responses.

Near the beginning of the novel, Paul quotes the opening sentence of Anna Karenina: "All happy families are alike; each unhappy family is unhappy in its own way." By the end of the novel, he has disproved the theory. His own happy family is unique, but happiness isn't everything.

 Louise Welsh's The Girl on the Stairs is published by John Murray. Herman Koch will be appearing at the Edinburgh International Book festival on 24 August. www.edbookfest.co.uk.

As I type this, hundreds, perhaps thousands of writers across the world are hunched in similar fashion over their own computers, pounding out stories of lissome young students having their bits clamped by dashing billionaires, nurturing their inner goddesses and frantically screaming safe words. Successful novels generate imitators that swoon in their wake like groupies, copying style and subject matter, but rarely capturing the zest or freshness of the original. Literary agents must be watching for that deluge of Fifty Shades rip-offs on their slush piles like Pacific islanders watch for tsunamis.

It is a rather better book that acts as the model for Dutch author Herman Koch's The Dinner, which has sold more than a million copies across Europe. Lionel Shriver's We Need to Talk About Kevin (2003) is still the best of a recent slew of literary works dealing with the impact of acts of violence on bourgeois family life. The success of that novel was driven by Shriver's cool-headed unwillingness to apportion blame between the evil son and his calculating, compassionless mother, so that the reader becomes a moral arbiter, forced to take sides in the nature-nurture debate. Like The Slap (2009), another novel to which The Dinner's publishers attempt to wed it in their accompanying blurb, ...Kevin was not a nice book, and left many complaining about the lack of likable characters, but the moral heft of the novel and the cool, anthropological eye that Shriver turns on her dramatis personae lifted it a cut above its companions on the bestseller lists.

The Dinner won't win plaudits from those looking for saintly protagonists, either. It is the story of two brothers, Paul and Serge, and their wives, Claire and Babette, who meet for dinner in a swanky restaurant in Amsterdam. Each of the couples has a 15-year-old son and, we discover, the dinner has been arranged to discuss a horrifying act perpetrated by the two boys. No Columbine-style massacre, this one, rather a kind of extreme happy-slapping, where a homeless woman was beaten and burned to death, all of it filmed and then viewed by millions on YouTube.

The Dinner bears one of those strikingly interchangeable subtitles  How Far Would You Go to Protect the Ones You Love?  which aim to hook in the browsing book-buyer, but in fact it isn't about this at all. Like We Need to Talk About Kevin, it is about the nature of evil, and the extent to which we can blame parents for the misdeeds of their children. The novel is narrated by one of the brothers, Paul, a former teacher. Serge, far more successful than Paul, is an up-and-coming politician and minor celebrity (I pictured him as Troels Hartmann from The Killing) and Koch nicely conveys the resentment and deep-seated competitive angst of brotherhood: "He sawed his own wood for the fireplace as well; sometimes it looked almost like a publicity shot for his election campaign: Serge Lohman, the people's candidate... a regular man like any other, the only difference being that few regular men could afford a summer home in the Dordogne." As the novel progresses, we realise that Paul's animosity towards his brother is just one of a host of resentments that simmer beneath the surface of his narrative.

It is not long before we guess that Paul is that most familiar of literary tropes, the unreliable narrator. A first-person voice requires us to enter into a pact with the narrator: we agree, for the course of the novel, to see the world through his or her eyes. This is why the unreliable narrator, handled properly, works so well. In a couple of recent examples  Sebastian Faulks's underrated Engleby and Henry Sutton's credit-crunch thriller Get Me Out of Here  the revelation that the narrator has been pulling the wool over our eyes is played so deftly that it feels like a shocking betrayal when the truth becomes clear. In The Dinner, the reveal is rather more predictable and pat, the reasons for Paul's duplicitous nature a confusing admixture of nature and nurture.

There's one other duff note. The dinner itself is described in tiresome detail, its various courses presented by a sinister maître d' with an ominously hovering pinkie finger and then analysed at length in Paul's narrative. The pretentiousness of the fare is clearly meant to hold a mirror to the corpulent self-satisfaction of its bourgeois protagonists: "The lamb's-neck sweetbread has been marinated in Sardinian olive oil with rocket... the sun-dried tomatoes come from Bulgaria." But in the land of Heston Blumenthal and bacon and egg ice-cream, it all came across a little gastro-pub and tame, the descriptions overly windy and censorious.

The Dinner lacks the weight and finesse of We Need to Talk About Kevin, but it is a well-paced and entertaining novel. It will sit well with The Slap and Christopher Wakling's What I Did (2011) on the shelves of those who enjoy seeing what happens when the cosy certainties of middle-class families are shattered, when the thin facades of decency and manners are wrenched aside, showing the brutal, violent creatures that lurk beneath the surface.