The Forgotten Waltz, By Anne Enright

An adulterous affair lies at the heart of Anne Enright's novel, her first since her Man Booker win in 2007. The storyline might be a classic one but, like Flaubert, Enright has created an entirely believable world in which nobody is entirely sure of their own motives.

The novel's narrator, Gina Moynihan, is a Dubliner in her mid-thirties who works in IT. It's at her sister's housewarming party that she meets her future lover, Sean Vallely, an older man with "too beautiful" eyes. Ironically, it's only because she feels so secure in her relationship with her long-term partner, Connor, that she dares to return the stranger's gaze. The moment of their meeting spreads through the novel like a stain.

Looking back from the present, Gina relates how the affair progresses over the next several years. The lovers also turn out to be colleagues, and their relation-ship is played out in foreign hotel rooms. Enright is at her funniest when exposing her heroine's contradictory emotions. In one scene Gina is head-over-heels in love with Sean, the next she finds herself "slightly repulsed" or finds "the actual sex was a bit too actual". Mid-way through their liaison, she's mortified when Sean acts like a professional adulterer and presents her with a Hermès scarf and a bottle of scent that smells like rain and fabric freshener. She even finds herself embarrassed, at an office meeting, by his choice of fountain pen.

Gina is a self-consciously unreliable narrator, spotting the flaws in her arguments even as she's making them. It's never clear to us, or to Gina, why she's destroying her marriage to the companionable Connor, but we are on her side even when she appears casually cruel or sour. There's little sympathy for Sean's daughter, Evie, or his seemingly remote wife, Aileen. "I got her straight off," says Gina "and nothing she subsequently did surprised me or proved me wrong." After her first encounter with Sean, Gina feels suicidal, or rather, as she puts it "the flip side of suicidal: I felt I had killed my life, and no one was dead. On the contrary we were all twice as alive."

Less important than the momentum of the affair is Enright's playful and beautifully expressed examination of how it feels to cross the line. As in the tradition of adultery novels, the adulteress comes to a bad end. Gina finally ends up living with Sean and acting as stepmother to the petulant Evie. There's no arsenic in store, just the mundane inevitability of everyday life.