The destructive gesture that sets in motion Christos Tsiolkas’s powerful new novel — winner of the Commonwealth writers’ prize — is, as the title suggests, an open hand briskly applied to the face of a spoilt three-year-old. Although a reader might be forgiven for thinking young Hugo had it coming, the problem is that the hand belongs to a man who is not his father. What’s more, the blow is struck in front of the guests at a suburban barbecue in contemporary Melbourne. Although the child is not injured, the reverberations of the incident soon affect the lives of at least a dozen people.

The man who strikes the blow is Harry Apostolou, a son of Greek immigrants who has risen to the upper middle class through his ownership of a string of auto repair shops. Hugo, who was about to whack Harry’s beloved son with a cricket bat, is the progeny of Gary, a failed artist, and Rosie, a clinging mother who still breastfeeds her son as he approaches his fourth birthday.

Rosie decides to press charges, a move that immediately splits the guests. Among those who think Rosie is overreacting are Harry’s Greek relations, most notably his cousin Hector, at whose house the party is being held, and Manolis, Hector’s immigrant father. Standing in Rosie’s corner is Aisha, Hector’s Anglo-Indian veterinarian wife, and Connie, Hugo’s teenage babysitter, with whom Hector is having a secret dalliance.

The pressure of the looming trial takes a toll on nearly everyone. Rosie’s long friendship with Anouk, a television producer, is sorely tested, as is her marriage to Gary, an alcoholic who might not have the bottle for the upcoming fight. As Rosie insists on dragging Harry to his potential ruin, her stubbornness begins to look like something darker and more complicated than a simple quest for maternal justice. A deep discontent with her earth-mother lifestyle surfaces. Recalling the delivery of her only child, she is forced to admit that “in the savage animal agonies of giving birth to Hugo a sadness had entered her that was to never go away. He had broken her, shattered her girlhood self”. The frailty of Gary’s radical artistic pretensions are laid bare when he puts them on the line against a bourgeoisie he abhors.

Aisha’s apparently contented life is also rattled when her support for her old friend Rosie forces her to take a stand against Hector’s overpowering clan. Although her marriage appears to be strong, the crisis brought about by that back-yard slap lays bare the compromises that entangle the relationship. “This, finally, was love,” she admits. “This was its shape and essence, once the lust and ecstasy and danger and adventure had gone. Love, at its core, was negotiation, the surrender of two individuals to the messy, banal, domestic realities of sharing a life together.”

Tsiolkas dissects his characters with a scalpel that is polished and sharp. Hector is a particularly fine creation, a man whose vanities and self-deceptions wage constant war against his better angels. The world-weary Manolis, who at 69 is losing his faith in God just at a time when it might come in handy, is also memorably drawn. The author is skilled at defining character through conflict. Tension percolates beneath the novel’s suburban veneer. The fateful barbecue is remarkably suspenseful, but even better is the scene when the arrogant Harry comes to Rosie’s and Gary’s shabby little domicile to make amends.

The author’s virtuosity enables him to use the smallest of moments to evoke a bustling, diverse, chaotic society constantly on the verge of erupting into open hostility. When the dignified Manolis tries to enter a coffee shop, he bumps into a young couple he assumes will make way for him, even though they have no such intentions. “Neither had been hurt, but they had looked at each other in momentary bewilderment? Manolis, rattled, stood there expecting an apology but the young man did nothing, did not move, did not say a thing. He just looked confused. ‘Excuse me,’ the woman had finally said sharply — an order, not an apology — and Manolis stood aside to let them pass.” The savage animal agonies Rosie felt giving birth would seem to afflict the burgeoning new Australia as well.

The Slap by Christos Tsiolkas

Tuskar Rock £12.99 pp483